My gf broke up with me today because I messed up. Last night I was drinking with friends, a guy kissed me and I kissed him back. I told my gf this morning and she's ended it and of course is extremely upset and hurt. This was the first time I've ever cheated on her and from this experience I know it would be the last. I know now, more than ever that I only want to be with her and would never jeopardize the relationship again. As for her, we've had some issues with her and a girl that she used to like that ended up becoming a friend of both of ours. I did not have any issues with them being friends unless my gf would put her before me and it bothered me because I knew that my gf used to like her. I had asked my gf and our mutual friend if anything ever happened and both of them said no. A year and a half later, my gf confessed to me that they made out twice before she and I got together. I was hurt because I don't like lying and I don't like being lied to. But my gf and I worked it out that same weekend and grew from there. As for the question of wether lying or cheating is worse? Well, I believe that both are horrible of course, but for me (and this may seem biased) lying is worse because it diminishes the trust that was there and as someone else said, is out of your control. With cheating, It happened once and I told her the truth as soon as I could, but I get that trust was broken with that too. That however can be fixed in my opinion. I believe that there are things that can be done to ensure that you are fully committed, loyal and faithful. With lying, that creates such an insecurity that you question wether the other person is lying more often. This relationship that I had with her has been a long distance (12 hours) relationship for 6 months and so maybe that plays a role in all of this. I don't know, but I'm just hoping she'll take me back.