I think it's depends on the relationship, really.
I work out, my husband at the moment does not. He's not morbidly obese or anything, but I'm in better shape than he is.
For us, it's not a big deal. Sometimes I wish I had a running buddy...but he's just not there at the moment. He doesn't give me crap for running because he knows I enjoy it and that it helps with my mental state as well as my physical well-being. Although he doesn't exercise, he's a VERY healthy eater, so he doesn't bring home "junk" or anything.
Plus... and this is going to sound totally bizarre... but I don't find muscular or super-fit men physically attractive... I have no idea why, but a little extra "meat" is fine with me (and actually preferred).
In a nutshell: it doesn't bother me.