I try to forget about bad relationships, mostly. Sometimes they still mess me up, though.
1.) I dated this senior in high school while I was a sophomore, he was 19 I was 15. I didn't see anything wrong with it at the time, because high school and a cool older guy liked me. He ended up cheating on me and continued talking to the girl behind my back. Stupid 15 year old me thought "everyone messes up sometimes, it's fine" and took him back because he seemed genuinely sorry. I ended up sleeping with him because I was afraid he was going to leave me and I was desperate enough to try and make him stay.
He did end up leaving eventually and then strung me along for months on end, despite having numerous girlfriends after me. I was devastated and when I finally had enough and moved on, he had the gall to yell at me for "not being there for him" like I "promised I always would". Sorry pal, I'm done.
To this day I end up getting unnecessarily flirtatious if I feel like my relationship is in distress.
2.) The guy I dated immediately after the guy above seemed alright enough, nice guy, smart. Really down to earth.
He liked smoking weed and he was more or less my introduction to it. Weed makes me sleepy, and I made it clear to him that it had that effect on me. He got horny while he was high and we had sex even though I wasn't totally into it. Okay, fine, whatever.
There was another time where I was crying to him about having relapsed with hurting myself right as we got intimate. We stopped and he consoled me before eating dinner. After eating, we went back to his room and I remember still being visibly out of it. He wanted me to give him a blowjob, and I just went along with it because I guess it had been long enough and I guess I was over being upset.
A third time we were trying out one of his kinks (sex in the woods) and I just broke down in tears in the middle of it because I was hot, dehydrated, exhausted, hallucinating, and I wanted to go home. He asked if he could at least finish himself off before we left.
ANOTHER time was when he wanted to fuck me while I had a fever of 101 and I couldn't speak because my throat was so sore.
Most of my sexual encounters with this guy were basically 'why bother saying no, we do this so much anyway despite odd circumstances, what's the point of it' based off of the above experiences.
He broke up with me because he stopped loving me. He broke up with me MONTHS after he actually stopped loving me. I was unknowingly being strung along.
I'm in a better relationship now (coming up on 2 years actually!! :-) ) but those relationships still have an impact on me and my behavior and how I see myself.
Sorry for any grammar/spelling mistakes, I'm on mobile!