Cheated once and only once. He was abusive physically and emotionally and I also realised I wasn't straight by that point (not out to anyone, not even really to myself) and I guess I had "fomo" and didn't want to spend the rest of the shitty relationship, however long it lasted, never having experienced sex with a woman - I was engaged to this dude and thought I was doomed to spend eternity with this asshole. I couldn't get past that want/need/desire, couldn't get it out of my head, would fantasise and dream about it... to the point where it was actually affecting me mentally/emotionally and I guess sexually as well. Met someone on Instagram, and long story short it was meant to be no strings attached but my dumbass got attached... Eventually got my heart broken and karma got me back. Wasn't a long winded affair, as soon as I realised I was in love with this new person, I ended the relationship with the guy and came clean about cheating. Gave me an excuse to get away in the end...