Yeah, this has happened quite recently. One of my mates has been with a girl he met in college for just under 2 years, he went off to Uni this year, single, and he used to come back every weekend to visit the lads who have stayed here, even though we used to chat on msn nearly every night anyway... Now about a month ago he said that he had got back with her after I saw a pic of them together as his display picture. Since then I haven't heard from, he use to text me from time to time, nothing, barely been on msn and he definitely hasn't bothered to come back to see us.
When he broke up with her, his words were "I'm not gonna ever put a girl before my bro's again" Low and behold a couple of weeks later and it's happen all over again. When he was with her last we barely saw him, he never bothered to come out with us, he didn't even bother going to the clubs/pubs with us, or not unless she was there and even then he wouldn't spend time with us and he'd be clung to her like a magnet the whole night.
We've always been there to support him when they've split up, this is like the 6th time they've got back together, so we've never disowned him in anyway and we're always here for him, but as soon as he gets back with her he completely forgets we even exsist, which I find quite outrageous to be honest...