I've been in a relationship for almost 4 years, my mate was going out with this girl and they split up, me and my girlfriend where there for him when he was single, he was always down at our house for tea and he stayed over a good few times. We totally looked after him.
He later found another girlfriend and what do you know, splat, dropped like a rock. No phone calls not texts, no lads nights out with him or anything. I was really annoyed.
Totally on the spur of things he called me last night and came round for a bit, and what do you know, he's complaining about problems with his missus! Again, as I always am, I was there for him to spill his guts to about his relationship issues, and again I gave him my advice.
Think the moral is that your mates are always there (Just as you are), girlfriend/boyfriends might not always be.