My [25M] partner [23F] of now four years kissed someone else last summer, we stayed together but it still hurts.

-- Thank you in advance to anyone who reads this with a mind to offering their opinions or guidance. It feels positive just to write it down and put it somewhere people can see it. I don’t really tell people about it but it’s a big part of my life.

Met my girlfriend in the summer through a mutual friend. We dated long distance (2.5 hours on the train) for a year. The next summer we moved in together.

The third summer she moved to start a one year masters course at a very prestigious university. I stayed in the city we had lived in together. I was also studying; starting an undergraduate course at the same time as a mature student. We 'knew' we could do long distance because we had done it before, in our first year.

Her course was extremely demanding meaning she was extremely stressed and unavailable. Her subject of study is extremely technical and I understand virtually nothing about it. Despite this she still found time in her year to help me a lot with my work.

When I met the friends she had made at her university, there was a guy (Male PHD student in her subject, about our age). He was funny, charismatic and handsome. I liked him, but I get kind of jealous and I told her I was anxious that she would be attracted to him. She dismissed this, saying that he was attractive but not to her, or that it didn't matter because she was with me. I can't remember exactly what she said.

At the end of the year, I started my holiday as she was entering her exam period. Her whole year of studying was riding on one set of exams...and I was on holiday. I had a job lined up but it didn’t start for a couple of weeks. So I had a good time partying with my friends and generally doing not all that much. I failed to be there for my girlfriend when she needed support, even after she had supported me with my work. She told me afterwards that this is where she started to think about breaking up with me.

She finished her revision, spending day after day doing nothing but study and eat, and sat her exams. Then we went on holiday with her parents. We had a pretty great time.

We come back from holiday and had a couple of arguments about I can’t remember what. I do think I was being a bit miserable and taking our relationship for granted. Anyway we travel down to her university city and I leave to start my new job, she’s sort of packing up her things to move it back to her folks.

Phone signal is bad at my new job. Two days in she calls me saying she needs to come and meet me to speak to me. This is weird because I’m in the middle of nowhere so I just insist that she tell me what’s wrong. So she tells me she wants to break up.

I was shocked and extremely upset.

I was up until about 5am writing to her about how I could change and be a better boyfriend. I sent her what I had written. She messaged almost straight back saying she needed to tell me something that would change everything. She said that the day I left she got extremely drunk and ended up kissing this guy (remember the guy from before?). She was so sorry.

I didn’t know what to do. I had just poured my heart out telling this girl how I loved her and I would be a better person for her and it was true. In the end we decided to keep going and I’m extremely glad we did. I still love her, I love everything about her. But I’m still so hurt by what she did.

She was in his bed. When I pushed her for details she couldn’t remember whether they had kissed for one minute or fifteen. To me there is quite a big difference. She promised me that making out had been the extent of it and I think I believe her. Sometimes it’s so painful still and I feel real anger towards her.

They had gone back to his with a friend to watch Adventure Time but the friend left them and went home. Adventure Time was, like, my favourite show but now I think of this every time I see it, or the city she studied in, or this guys first name, or any of her friends from that city, or just at random every day.

It’s like when I feel sad this is where I go. I wish I could erase it from my mind; I wish I didn’t know.

tl;dr: Girlfriend kissed another guy after emotional neglect. It was just over a year ago but I’m still hurting.