It was when I was 27 years old, I was at my friend's wedding with HB 7/10 I thought was orbiting me but I got metaphorically bitchslapped when she told me around 11 PM that "she needs to go and her other friend is picking her up" - her father was well known scientist in my country at that time, her mother was retired from high ranking official position, generally speaking she was of "better" social background than me and she had a lot of loaded buddies - I was not one of them. So around 11 PM my "date" is picked up by some guy in a shiny BMW - thankfully rest of guests didn't give a phuck about me so nobody noticed this awkward and humiliating situation at first but I was internally furious by it and wanted to somehow confirm I am not a wuss and pushover I felt I was at that moment (I kind of planned some loser alcohol-fuelled move on my date before which would be poor idea anyway).
So there was this HB 7/10 wife of my other colleague that seemed to like me, sitting next to me that was really interested in where my date went - I was already loading up some drinks too fast so I said that she left - then I didn't pay much more time for thinking, looked her into her eyes and put my hand on her knee under the table, not paying much of attention to the fact that her husband was sitting 1,5 meters from me looking the other way at that moment. Guy didn't notice what I did. At that moment I thought "now I am going to get burned" but instead of that I saw lust in her eyes. So I whispered to her ear "let's go out from here"
Fast forward 5mins I was kissing her and fingering her through panties behind the building where the wedding party went. Later on I kind of got back my senses told her we should go back and did not initiate anything through the rest of the party but she was grabbing my leg and my c*CK through my trousers under the table. Later on she called me multiple times and met with me couple of times for a drink, told me she wants me etc. that her husband is a wuss and I am more manly than him but I told her that he loves her and I cannot do it something like that to him and her and that she will regret hooking up with me (ok I kind of made our with her once during these meetings but did not take her to my place).
That was the begging of my transition period from good guy to rookie PUA which I am somewhat ashamed about right now but it was clear to me that I never wanted to be in a marriage that looked like marriage between that girl which did not slap me for my behaviour that night and that poor guy. Years later I noticed they have a daughter together (alas I am not sure whether it's his child taking under consideration his wife interests in other men).
This situation was also one of the reasons that formed my strict criteria for wife material: younger than me, inexperienced, from good traditional family, preferably a virgin, no interest in keeping male friends if dating me, submissive, not a feminist, w/o financial leverage over me (that's why I married several years later, after I got some material possessions and position in my life - my wife is living in my apartment and using 95% of things that are mine except clothes and personal belongings or things that we bought together - this also keeps my rather dominating mother in law in check when she visits - she remembers where she is and she is nice. She gets more bossy when we visit her but I keep my stinger ready or such situations.
So, anyway, yes, I was in this situation. If you marry hypergamic female, it's on you, not on the guy that made a move. Sorry, that's the truth. Be smart or be hurt.