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by Abigail Van Buren

DEAR ABBY: My mother-in-law is 84 years young. She is dating a 58-year-old man. They met 18 months ago and see each other every night. On weekends he picks her up and they go to his place from Friday until late Sunday evening. This man says they are compatible.

"How can this be?" my husband and I ask. At times she doesn't even remember being with him the entire day before.

Abby, this man is younger than her four sons. Each of them has tried to talk to their mother about this relationship. She sometimes "hints" that the relationship is sexual, making comments like, "Well, at least I don't have to worry about getting pregnant."

She can't be talked to or reasoned with, because she starts screaming that her family is "jealous" and trying to "break them up."

We're at our wit's end and don't know where to turn. She has money. He has none. Thank you from the bottom of our hearts if you can offer any advice. -- READY FOR THE BOOBY HATCH, JACKSONVILLE, FLA.

DEAR READY FOR THE BOOBY HATCH: If your 84-year-old mother-in-law's memory is impaired to the point that she doesn't remember having spent the previous day with her gentleman friend, one wonders how she is handling the rest of her affairs. Is this the way she has always behaved?

If the answer is no, she may be due for an evaluation by her physician to determine if she is still capable of handling her financial affairs. If a medical examination confirms that her memory lapses are severe, the family lawyer should be consulted to ensure that she cannot be taken advantage of financially.

Once that precaution has been taken, I see no reason why your mother-in-law shouldn't continue a relationship that both she and her friend enjoy.

DEAR ABBY: I have planned my last party. Out of 45 invitations mailed out, we had three RSVPs! The invitations clearly stated a date by which we needed a response, and still only a tiny percentage complied.

My husband and I would not have been as upset if those 42 people had called with their regrets. But sitting around and wondering how many, if any, people are going to show up is nerve-wracking. I had no idea how many people to prepare for, or whether we needed to rent tables, chairs, etc.

The same thing happened with our wedding invitations. They included a response card and a self-addressed, stamped envelope (all they had to do was indicate whether they were coming or not, and put it in the mail), but many people never responded to the invitation. Some showed up without letting me know they were coming, and others failed to show when they said they would.

Has something changed? Why do people think it's OK not to respond to an invitation when specifically asked to do so? -- FED UP IN MILWAUKEE

DEAR FED UP: Nothing has changed. "R.S.V.P." stands for "repondez s'il vous plait," and translates to "please respond." To ignore an invitation, and neither accept it nor politely refuse, is inexcusable. It takes only a moment to make a call or return a written reply. However, if people haven't responded in a reasonable period of time, I see nothing wrong with calling them and asking if their decision is "yea" or "nay." As a host or hostess, you need to know how many guests to prepare for.

Everybody has a problem. What's yours? Get it off your chest by writing to Dear Abby, P.O. Box 69440, Los Angeles, Calif. 90069. For a personal reply, please enclose a stamped, self-addressed envelope.

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