I experienced a similar feeling towards my previous long term boyfriend (before getting married). It felt like we were just flat mates. I felt really guilty bringing it up to him, because he hadn't actually done anything wrong - we still got along well etc, but there was no spark, no intimacy. I think humans crave intimacy with other humans, which is one of the reasons we tend to partner up as opposed to living solo.
My ex and I went our separate ways BUT we had no children in the picture, we weren't married, we didn't have a house together - it was easy to walk away. In your situation there is more at stake. It's very normal for couples to drift apart and back together throughout marriage...it would be lovely to constantly live in the 'honeymoon phase', where you get tingly thinking about the other person, and where you have sex five times a day...but it doesn't work like that! Marriage is hard work! Throw a baby into the mix, and it's even harder still (pp is absolutely right about relationship dynamics changing once children come along).
So...it sounds like you need to reignite the flame. I would suggest engaging with a marriage counsellor as soon as possible. I would suggest each of you doing things apart from the other during the week, so that you have an opportunity to actually miss each other, and I would definitely without a doubt suggest date nights
Sending many hugs