when I was in a romantic relationship about a year or so back I ended up technically cheating on them (I was drunk + we were playing truth or dare/dare or dare)(it was only kissing also). I was completely transparent about the whole ordeal, telling them the day after, knowing that it wasn't the first time I kissed someone when I was with them and they didn't seem to be bothered about it. They made a whole thing of it this time, making me make a groupchat with them and my friends (which was a mess because of language barriers and it made the whole thing worse) even after I apologised multiple times and tried to make them understand that it was mistake and that I was extremely sorry and that it was a one time thing.
I understand that it was something done without their say in it and that looking back it was wrong for me to that in that relationship, but at the same time they were sending mixed signals.
It was a learning experience in some ways, making learn that I should talk over the yes and nos of a relationship before hand (especially since I discovered I was aro which add complications sometimes).
If I put myself in their shoes, I can see why they feel bad. I did something that I still hadn't done with them (we were in a ldr) with multiple different people. It was a break in the trust they had in me. I don't understand why they made me wrap my friends into it, counting that it was something between me and them, but they felt it was needed and that's fine).
(At the same time I might of not understood why they were making a big deal out of it due to the fact that I'm aro and I don't fully understand how romantic feelings work)
I understand what you mean by not understanding why people make a big deal out of it in some situations.
Ironically they cheated on me at the end of the relationship without telling me anything, which hurt more. If they were transparent about it would of hurt less, but still I didn't make a fuss and just moved on.
It's something I don't feel should be made out as a big deal, especially when you aren't living with the other person and aren't financially dependent on them and when you're in high school or middle school (of course they are certain situation like if you're married which makes it bigger and more complicated to sort out).
But in conclusion: relationships tend to be messy if no rules are set up before hand and sometimes it's better not to be in one if the other person can't respect or understand why you need those rules.