Hahaha, I know how you feel, sometimes we just have to laugh at the insanity of it all.
My ex would do the same things. He had all these ideas of how he wanted to just get married, and have kids, and then everything would be fine. That's when he would become more responsible, and get his stuff together, fix his finances, start taking care of himself. He actually told me all this once, that he was waiting until after we had kids to do these things. I just had to laugh, because he really thought the words coming out of his mouth made sense, and that I would think that was marriage material.
Every time he started one of these 'conversations' about how "we're not getting any younger Kitty, it's time for me to settle down and become a father", it just helped me see even more clearly that he wasn't a healthy partner choice for me. Our ideas of acceptable, mature behavior are so different, and it wasn't worth the argument anymore. Trying to make him see that he was still a child himself was a moot point.
When I left, he was actually mad at me because he was researching engagement rings, and was going to pop the question this summer, and I was ruining it all. The fact that I had been telling him for months that I wasn't happy with how things were, none of it ever sunk in. It was almost insulting to me that he thought I was naive enough to marry and reproduce with him, but that's just more proof of how sick he is I guess.
Thanks for sharing, now I don't feel so bad when I laugh at things my A used to do!