Wild. I went 22 years without ever having a desire to kiss/cuddle/romance a guy, so I considered myself 100% straight, but once a girl I dated for like 6 months invited an "alpha male Chad" type ex to threesome with us. I was so jealous at first, because he basically made my girlfriend forget I was there at all with how well he knew how to give it to her... but by rage/bitter feeling slowly became more of an interest in being submissive to him? whatever that counts as. After my girlfriend couldn't take anymore, she asked me if this could turn into a MMF and I would bottom for him because he was still not near completion. I was a little intoxicated so it seemed like a good idea to me, like I could never outtop him so my only choice was to be a better bottom than my girlfriend was. All I wanted was not to be "third place" in the threesome, I was so competitive at that time in my life. She sweetly flipped me over to lube me up and line up his giant mushroom head with my opening, It hurt so bad at first as he pushed it in but after he totally bottomed out it felt like his manhood had been created just for me, like we were 2 puzzle pieces. He would tease me and do these long strokes all the way in and out, every time he pulled his tool out of me it felt like I was incomplete, missing something I never knew I needed. The orgasms I had whimpering for this guy while my girlfriend was telling him to go harder on me were so transcendent and blissful... I had the overwhelming desire to just smile and kiss him as we finished together. He had cum on me and because I'm so hairy I had to go wipe up in the bathroom... When I came back he laid in the middle of the bed with my girlfriend curled up in one of his big strong arms just absent mindedly giving his torso little love drunk kisses as he nuzzled her scalp. Sorry if it sounds corny, it set my emotions were on fire, it felt like pair bonding hormones were flooding my brain, at the same time I felt totally resentful/inadequate from being physically outclassed, so I just went to sleep on the couch.
After that night I couldn't leave well enough alone and kept trying to argue with my girlfriend that she "forced" me to do it and ended up ruining that relationship because I couldn't accept my emotions at that point in life.
I've never done anything same sex again, and I'd never want to kiss and flirt and be in a relationship with a dude and all that so I basically assume it'll never come up again, but I can totally see why gay guys get fulfilled by how amazing the act is. Straight guys don't realize how there's kind of a spiritual feeling, it's not just punishment