Can I give an alternative point of view?
I think the easy thing here is to be (rightly) angry at Aimsmum's DP's approach. Implicitly, and emotionally, it pisses me off that someone can even think like that
BUT (and no doubt I'm going to get flamed here)
He has no experience of living with children. He doesn't even have much experience of anyone else living with children. Generally, people (especially guys) with no experience of living with kids finds it incredibly hard work being around them. I can see it with my childless friends - a mate will come round to watch the football and (still) be surprised that we won't be idly sitting on the sofa with a beer chatting but rather having DD clambering on us, shouting, demanding "Beebies", running around etc.
I'll be honest, before I had a kid I didn't especially like being around people who had kids. To us, as parents, they're wonderful, special, absorbing and delightful. But to many people (again, especially guys) without children they're loud, they're annoying, they constantly demand attention and they screw up "fun" things, like going down the pub. Before DD, going round a friend's place who didn't have kids was one hell of a lot more fun than going round someone's who did.
I think my point here is that there's no way, even if he thinks he can, that he can imagine what it would be like if he actually did live with you. That the dancing goes hand in hand with the cuddling. That the singing goes hand in hand with bedtime stories. It's easy just to see the negative bits, until you see how they go with the good bits. Does that make sense or am I just talking crap?