Are you male? I don't want to assume. But as a woman this is something that really concerns me about the guys I and my friends date. I see my father doing the same thing. Once they get into a stable relationship they seem to think that there's no need for a social life beyond their girlfriend, coworkers, and maybe one or two very close old friends... but those old friends tend to drift away.
The reason it bothers me is because these men end up overrelying on their girlfriend or wife for both emotional support and to manage their social life. Without the woman doing it for them, they get angry, misanthropic, and antisocial due to not having an outlet - and they don't see it as a problem at all. But their families get to watch them become more unpleasant and withdrawn as time goes by.
This is something I find really hard to talk about with the men I see doing it, especially when it's my own partner. Obviously it's not all men. But my dad DEFINITELY does it, and the result is that he's gone from being a fairly open-minded, liberal, and environmental kind of person to someone who can't seem to talk about anything other than guns, American politics (we're not even American), and the "idiotic" policies of our local politicians. He recites stuff he's heard on TV as if it's gospel truth. It seems impossible to have normal, non-political conversations with him anymore, he just doesn't have any knowledge or interest that doesn't come from TV.
He's my dad and I love him, but needless to say, when I see my partners going down the same path, it freaks me out. Sorry, I know that's a lot to extrapolate from your very short comment, but maybe it's just something to think about.