<human>: We have been fairly serious about each other, and have known each other for 7 years. We were together, and now in a long distance, with an end in sight (2 more years) after which we would be married. Long distance is not really a problem for either one of us as communication has become so easy and quick. 

I recently was traveling the world and journeying back to the city we share to spend time together. However, one of those destinations on my journey, I met up with a good friend of both of ours. We decided to go to the bars and have a few drinks, one thing led to another and I end up blacking out that night and I thought that was it. I let me partner know what we did to the best of my knowledge that we had gone to bars, clubs and strip clubs.

Fast forward to a few months later, we are comfortable enough to come out to our families and while we are in the process, the friend mentions about the night of bars and clubs and how I end up making out with someone. 

Now, a little bit about me. I consider myself an okay person. Not great by any means, but not terrible. If I had known about it then about this "make-out", I would have told my partner immediately because otherwise the guilt would have eaten me up. 

Being in long distance requires trust and now she feels she cannot proceed any longer. I feel horrible for making her go through this and to even cause her any pain. What can I do? Is this a lost cause? How do I prove to her my loyalty? I can give up drinking if that's what needs to be done. I understand it's my mistake, but there really is no intention or motivation for me to do anything like this.

Can you provide a brief overview of the text?
<bot>: OP is dating someone. Currently long distance. OP made out with a random stranger and found out himself months later. GF has lost faith and OP doesn't know what to do.