DEAR ABBY: We recently found out my 19-year-old daughter is pregnant. This is her first boyfriend, and she is absolutely smitten with him. He has asked her to marry him, and we are excited and happy for her, but there is one thing we are having a hard time with: I am almost certain he is cheating on her.

They live with us, so I can see the signs — he says he’s working late, and several times even told her he had to work all night. He’s always on his phone, and he never allows her to see it. He keeps it on silent and face down. When he gets a text message (which is often), he immediately says he has to go to the bathroom. Then he stays in there for about a half-hour.

I’ve tried talking to her about what I’m seeing, but she gets mad at me. She says she trusts him and insists he would never cheat on her. It’s painful to watch this happening to her, and I don’t know how to handle it. Should I continue bringing it up or let her find out on her own? — KNOWS ALL TOO WELL

DEAR KNOWS: You have already brought it up. Your daughter should not rush into marriage just because she is pregnant, if that’s her intention. Because her boyfriend is living with you, he’s likely not mature or financially stable enough to be married to anyone. (What do his parents think about this?)

I was tempted to advise you to hire a private investigator to find out if the young man is really working late or all night, but I’m not sure you need to go to that expense. The truth will eventually reveal itself. In the meantime, give your daughter plenty of emotional support because she is going to need it, and probably more.

DEAR ABBY: I married my high school sweetheart in 1967. In 1979, after 12 years of marriage, we refinanced our mortgage so we could add a room. During the credit check, it was brought to my attention that my wife had borrowed $14,000 and opened a secret mailbox in a different town to hide it from me.

The problem was, and still is, that she has refused for 52 years to tell me what it was for. Needless to say, my trust in her was shaken. She had no drinking, gambling or drug problems. I must have asked her a thousand times what she needed the money for, and still no answer. Our marriage went downhill, I had an affair, and we separated.

In 1990, we got back together, but it wasn’t the same. The kids were grown, so four years later we divorced. I’m 75 now, remarried 20 years ago, and I still can’t figure out why she couldn’t tell me the truth to save our marriage. (Abortion keeps popping into my mind.) A day does not go by that it doesn’t enter my mind even all these years later. My kids are estranged because all they know is that I had an affair. I suppose I will be wondering until my dying day. Advice? — STILL IN THE DARK

DEAR STILL: What your ex-wife needed that money for is anybody’s guess. She may have used it to bail out a friend who was in trouble. She also could have been paying off a blackmailer. The possibilities are so varied that guessing her motive could be a parlor game.

Since you asked, my advice to you is to finally let the past stay in the past and quit upsetting yourself over something you will never get a straight answer about. There are few more effective ways to diminish the joys of the present than to do what you are doing.

Dear Abby is written by Abigail Van Buren, also known as Jeanne Phillips, and was founded by her mother, Pauline Phillips. Contact Dear Abby at www.DearAbby.com or P.O. Box 69440, Los Angeles, CA 90069.