I was thinking more about this thread and I had two more thoughts.
One -- Is your husband adjusting to being the primary income earner? I know that was a difficult psychological adjustment for my husband -- to have it all fall on his shoulders. I also think in retrospect that my DH didn't really bond with our babies until they could *do* something. So he may be struggling with his role as primary income earner & not quite bonded with his babies yet.
Two -- I thought 5 months was a hard age. I was ready for them to be able to do something -- sit up and chew on a toy, something like that. They took up a lot of time, more so than they did a month or two later when they could sit up and I could chat with them while they played and I folded laundry. Also, the time with them is precious. You're not going to get it back & your job is them, if that makes sense. Not that you have to ignore everything else and stare at them all day, but before you know it, they'll be big and their baby selves will be a memory and it's gone. I know I'm rambling, but face time with them, playing, reading, singing is so important.
Anyway, I hope he can understand where you're coming from. I told my DH all you were doing and he was impressed!