Don't worry about it. This has happened to everyone I know,
(except myself - apparently she never knows where she stands with me which I think means every day is new and exciting - so that's nice)
...but the trick is to make sure you don't accept this situation.
A good screaming match alway sorts it out. Make sure your fella's home at the time though. Or it sort of misses the point.
At least he goes to the gym still. Could be worse he could just be a fat lazy bastard. Go out for the day, even if it's just to the Park or something. And make each other laugh!! Seriousness is a fatal disease.
Or buy a cat, that will give you a common focus for your affections and you will see if he has a parental instinct.
I now have ten cats. And no kids. But we never have time to argue, we're too busy defleaing the house.