Fair play to him. Standard lad behaviour tbh
However, if your girl is prepared to sacrifice your relationship for a guy like that, she isn't worth sticking with (unless for casual pasty smashing)![]()
How about this then?
You are going through a VERY rough patch in your life, and it has had a detrimental effect on your relationship.
Over time, things would get better, you would work through your stuff and the two of you will live happily forever after, as getting through the rough patch strengthened your relationship.
Only this doesn't happen, as during the rough patch, when being the partner you should have been wasn't possible, some guy tempted your gf away from you.
You weren't intentionally being a bad partner, but at the time, you could see why she could be tempted away. If that other guy hadn't stuck his nose in, 6 months later everything would be fine.