DEAR ABBY: Three months ago, my longtime boyfriend, "Mark," broke up with me. We had planned to be married. It took me a long time to get back to being my old self.

Right after our breakup, Mark began dating his boss's daughter. I'll call her "Carrie." I accepted it because I care about Mark and want him to be happy.

My problem is, for the past month, Mark has called me frequently in the middle of the night to tell me he "misses me" and how much he "continues to love me." He's even said he still wants to marry me.

Every time Mark calls, he invites me to come over and sleep with him. I have refused because of Carrie. I feel sorry for her.

Abby, I cannot imagine being with a man who is still in love with someone else. Should I tell Carrie what Mark is up to -- or should I stay out of it? I am awaiting your reply. -- MARK'S EX

DEAR EX: The first thing you should do is fall on your knees and give thanks that you are no longer engaged to this two-timing user. If you are wise, you will stop all contact with him. That said, if you try to warn his boss's daughter, she will probably interpret it as jealousy and not believe you. She needs to find out about him on her own. And when she does, Mark will be looking for another job and another gullible woman.

DEAR ABBY: Our family recently attended my daughter's high school graduation. Seated next to us was a couple who talked to each other during the entire commencement -- until the man's cell phone began ringing. Then he continued to carry on a loud conversation over the phone. Needless to say, it was a major distraction for all of us who were seated near him.

This is not the first time such a thing has happened, and I know it won't be the last. People who talk while others are trying to listen do not seem to care that they're disruptive and disrespectful.

This happens everywhere nowadays -- church, business meetings, movies and plays. Growing up, I was taught to listen with respect and never interrupt others.

I have tried to politely ask the offender to "keep it down," or have gotten up and moved to a quieter location, but sometimes it's impossible.

Has our society gotten so "me-oriented" that we've forgotten the common courtesy of being quiet while others are speaking? Maybe you or your readers can share what works for them in order to stay calm during situations like this. -- LOSING MY COOL IN LYNCHBURG, VA.

DEAR LOSING MY COOL: Cell phones are a boon to many people. But used thoughtlessly, they also create very real problems. Of COURSE people should observe the rules of common courtesy and turn them off at public events. And people who converse on their cell phones in public places should remember to do so discreetly -- not only because to do otherwise is inconsiderate of those around them, but also because they can unwittingly reveal personal information that could come back to haunt them.

To order "How to Write Letters for All Occasions," send a business-sized, self-addressed envelope, plus check or money order for $5 (U.S. funds) to: Dear Abby -- Letter Booklet, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included in the price.)

DEAR ABBY: Somewhere in this great country there's a town or city that will win $25,000 and national recognition by entering the National Organization on Disability's 2003 Accessible America contest. Anyone who feels that his or her community is a model of accessibility -- a place where people with disabilities can fully participate just like anyone else -- should encourage the mayor to enter the contest before the Oct. 31, 2003, deadline.

When communities make the commitment to improve accessibility, all of their citizens and visitors benefit. One-fifth of all Americans have some sort of disability. That's why it is crucial that communities ensure a safe and welcoming environment. The Accessible America contest puts a spotlight on those cities and towns that are leaders in improving the quality of life for people with disabilities.

As vice chairman of the National Organization on Disability (NOD), I urge mayors in towns large and small to place a priority on creating a level playing field for all citizens by providing equal access to their services and facilities. I encourage them not only to share their successes by entering the contest, but also to join NOD's Community Partnership Program on behalf of their constituents. It's a great way to learn how best to comply with the Americans With Disabilities Act and to get tips on maximizing access and opportunities. -- CHRISTOPHER REEVE

DEAR CHRISTOPHER: Count me among your many fans. I'm pleased to publicize such a worthwhile endeavor.

Readers, the NOD Community Partnership Program is sponsored by the Alcoa Foundation, and the Accessible America contest is sponsored by UPS. I salute both for their community involvement.

To learn more about the contest, call (202) 293-5960 or visit the NOD Web site: www.nod.org. I'll put the name of the winning entrant in my column in December.

DEAR ABBY: I am 16 and attending summer school. My sister, "Maria," is a year older than me. She's new to our school because she just moved here to live with our mom and me. (She was living with Dad, but he kicked her out.)

Since the day Maria set foot on campus, every guy here is after her -- and I know why. She wears skimpy clothes and has a big chest.

Now every boy I like ends up liking Maria instead of me. I'm sick of it. There's only so much a person can take, and I've reached my limit. Do you have any advice for me, Abby? -- EXASPERATED IN NEW MEXICO

DEAR EXASPERATED: I'll begin with some words for your mother, because she is the person who is going to have to deal with your sister. There is a time and a place for everything. Maria is crying out for attention, but she's getting the wrong kind -- and unless there is intervention, she'll wind up in trouble. Your mother should make it her business to find out what is proper attire at your school and enforce the dress code.

Now, some advice for you: Sibling rivalry is normal -- the attention your sister is attracting is transitory. Concentrate on your grades and on activities at which you can excel. That way, you'll be an outstanding individual in your own right and not just "somebody's sister." Trust me, it'll pay off in the end.

P.S. Please clip this column and show it to your mom.

What teens need to know about sex, drugs, AIDS, and getting along with peers and parents is in "What Every Teen Should Know." To order, send a business-size, self-addressed envelope, plus check or money order for $5 (U.S. funds only) to: Dear Abby, Teen Booklet, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included.)

DEAR ABBY: My recent eighth-grade graduation should have been a happy night for me, but I spent most of it in the bathroom with my best friend, "Sandy." She was crying her eyes out because her father was there. She hadn't seen him for more than two years. Sandy's mother had an affair with him 14 years ago, and he decided to stay with his wife, leaving Sandy and her mother alone. Her father pays child support, but his absence has left an emotional gap you could drive a truck through.

Sandy's mother is a wonderful person, but you can't talk to her about important things. And Sandy isn't open about her feelings to many people. They build up inside her and she just explodes. Seeing her father on graduation night was the straw that broke the camel's back. He seemed uncomfortable. He barely spoke to Sandy and didn't give her a hug or anything. I try to console my friend the best I can, but I'm not sure what to say. Abby, if she starts to feel bad again, what can I say to help her heal her pain? -- CONCERNED FRIEND IN WISCONSIN

DEAR CONCERNED FRIEND: Continue to be the caring and supportive friend you have been. However, rather than trying to heal her hurt, tell your mother what you have observed and ask her to speak to Sandy's mother. Sandy will need counseling and a safe place to express her feelings of hurt and abandonment. If she sees someone now, it could save her years of unhappiness and therapy later. Her feelings are valid and must be addressed.

DEAR ABBY: Our daughter, "Lea," went away to college last year. She was looking forward not only to the opportunity to learn, but also to make new friends. She had made only a couple of friends in high school. During her freshman year at college, Lea made an effort to make friends, but never made more than one.

Lea is returning for her sophomore year, resigned to being one of the less popular students. Have you any suggestions or a booklet of some kind to help her? Lea is a bright, attractive young woman who deserves to have friends. What's her problem, Abby? -- SAD MOTHER IN SANDUSKY, OHIO

DEAR SAD MOTHER: You haven't given me enough information to determine what has prevented your daughter from making friends. However, I do have a booklet that other people have found helpful; it's titled "How to Be Popular: You're Never Too Young or Too Old." To order, send a business-sized, self-addressed envelope plus a check or money order for $5 (U.S. funds) to: Dear Abby -- Popularity Booklet, P.O. Box 447, Mount Morris, IL 61054-0447. (Postage is included in the price.) Allow six to eight weeks for delivery.

DEAR ABBY: My 38-year-old son was recently sentenced to 14 years in prison for molesting his 10-year-old stepdaughter. I am devastated.

Do you think I should seek out the girl and tell her how sorry I am? She and her mother live several hundred miles away. I feel my son has ruined this young girl's life. -- STEP-GRANDMA IN ALABAMA

DEAR STEP-GRANDMA: By all means let the child know you care about her well-being. Let her know that you empathize with her pain and are there for her. Right now, the girl needs to know that she is loved and that family members support her. You can accomplish this by reaching out.