Is it normal for your boyfriend to stop smelling good with time?

Perhaps he's making less of an effort to smell nice. Or it could be that at the beginning of the relationship, you liked him, but now you're no longer attracted to him. Not liking your lover's smell can be a sign that the love is fading.

Yes, they care less as they progress into the relationship, my gf approves this.

In other words at the beginning of the relationship you like them then..you don't.

You're probably just more attuned to the smell when the relationship is new, because the smell is new. Over time, like anything you grow accustomed to it so it just becomes something you're overly familiar with, nothing special.

That, or your boyfriend has stopped wearing deoderant.

They should probably wash themselves more often if they start to smell after a few weeks.