I(22M) screwed up the relationship of my friend (22F)

We’ve know each other since the beginning of the year, we were in the same class,we sat next to each other and sometimes we came to each other’s houses. You could tell that we weren’t just ordinary friends. We shared a lot of moments together, when she was sad, I was there to comfort her.

So, It happened this friday. It was a normal day at school. We studied economy. During a break given by our teacher,we went out to get some food. After that we sat on a bench and ate our food. And as we did,she received a message, I Saw that she had a worried look as she quickly ran away. I didn’t think much of it at that Time so I finished my food and went back to class. As I pass the door I see that she’s face up against the desk. I sat next to her and I saw in her phone that she was in the middle of an argument with her boyfriend(he isn’t in the same university as we are). That dispute seemed to really affect her.

After the class was over it was time to go home. I couldn’t bring myself to let her go by herself in her state so I kept her company. Throughout the entire route she was silent. As we arrived at her home she went to her bedroom as I followed. She sat on her bed and I sat next to her. She was really depressed. I figures that she certainly broke up with her boyfriend. So I did my best to comfort her. I tried my best to make her smile with some funny videos on Instagram. And it worked,she was clearly less sad. We went on and watched more videos.

And then,After some Time,she kissed me. I didn’t know how to take that so I was a little bit confused,but I played along and kissed her too. We ended up doing it. I made sure that she wasn’t sad anymore then I left. Little did I know that they didn’t break up yet. She didn’t tell me, I should have asked. I knew later that I was the reason of their dispute and now it looks like their relation’s really coming to an end,because of me. So i’m asking you,what should I do or what should she do to fix the situation? We screwed up,we never should’ve done that. I need your help,your advice.

TL;DR: My Friend was depressed after a beef with her boyfriend, I thought they broke up so I tried to comfort her to make her feel better,and she kissed me,things happened,but they still were together despite the long dispute,so now their relationship’s falling apart.