Dear Amy: I’m writing in reference to my recent engagement. I was alone for a long time and met a woman at work and fell deeply in love with her. Two nights a week, she comes to my place for dinner, and we are intimate. Then she leaves at 10 p.m. Two months ago, I asked her to marry me and she said yes! But our situation is very unusual. She lives with the guy she has been with for 15 years.