I've never met a guy who doesn't want sex with their girl at every opportunity they can get. Thats of course unless they are gay.

How is it offensive to girls? Each girl have their own sex drives. Some of my girl friends have a very high sex drive and their bfs are more than happy for it. While as some girls, like my gf, have quite moderate to low sex drive. But I'm not complaining either.

I think if you're doing it too often with your gf, they might think that you're only with them for their body and not for their heart. IMO, that would be quite offensive to some women unless they are doing the same thing. But that might not be the case if both parties understand that they are merely just "FUBU".

In my first year of relationship, I would say I used to get a lot of sex. At least once a month (still too hot for each other and always touching here and there). Second year, at least once every 2 months (starting to get busy with work and don't get to see each other much). Third year, none at all (hardcore busy and a lot of traveling. When I want, she not free. When she wants, she's having period ). Fourth year, so far 3 times since May.

So I would say sex is not a must for relationship to go strong. Its just some added advantages. Though I've seen a few friends who do wish to remain virgin until they get married and some of them had been together for at least 8 years. So yeah, sex is not a must.