You and a lot of other guys.
I did when I was first dating my wife. She was still living at home going to community college. Her mum was home and my girlfriend was in class that day. She wants to get to know me more than what her daughter was telling her. We talked for a long time and the conversation about sex came up. She said she doesn't want her daughter to be pregnant before marriage. I told her I feel the same and I respect all women young and old regardless of age. She was please to hear that. I told her how beautiful she is how she keep herself looking so good. She said thank you and I walk up to her giving her a hug and getting ready to leave.
She grab me and push me down on the couch and kiss me on the mouth. I didn't resist and return the kiss. She was straddle me on the couch kissing me and my cock is getting hard. She can feel it because she kept moving around. I left her dress up pull her panties aside and she sat on my hard cock and continue kissing. She was riding my cock to the point I cum deep inside of her pussy while we were kissing.
She told me not to say anything to her daughter/wife now. We kept this affair going until I marry her daughter then we stop.