I'd question any woman who was ok with having her son around when we had sex. That is simple. Call me a prude but protecting our children comes before any other needs. You get one shot to do it right and raising your kids on your own makes it twice as tough. Let's think about the little guy first. If you're not "into" him - forget her.
I'm with Barb. I wouldn't be able to be intimate with a man if my younger kids were home. I did have a situation this summer when my 22 year old daughter was home and I felt weird having a guy over. She was already in bed when we got there, but it still felt odd to me. My dating/going out with friends pretty much only happens when my kids aer at their dads. Not sure how I'd handle it if they didn't go to him regularly!
"You can't stop the waves, but you can learn to surf." Jon Kabat-Zinn
