I was thinking about this for an hour or so earlier this morning, and thought I'd try to put my thoughts down here and see what input the Queens of FDS have. Please link similar posts if they have been made.

Here it goes: I think men get infatuated much easier than women do, and they call this love. This seems to be the base for the stereotype of a man meeting a woman and thinking instantly that "she's the one." While I certainly have a romantic streak, can you really know that in like 10 minutes of meeting someone? Now, occasionally they end up being right, and the relationship ends up being a fulfilling one for both parties. But often men just have the hots for a particular woman, and once the physical attraction dies down, particularly after she's gone through some body changes after pregnancy, for example, they're very "meh" about her, if they don't outright resent her.

That's when we get all those horror posts about husbands berating their wives for not being skinny enough post-partum, resenting her for spending more time with the children than him, cheating while he has a baby at home, ad naseum. To me, this indicates the husband or man in question didn't really love the woman in the first place. If anything, having children together with someone you love should enhance your relationship and your affection for them, rather than the opposite.

Yet this doesn't happen frequently in heterosexual relationships, because the only reason the man "picked" a woman to be his wife (or girlfriend) is that he was extremely physically attracted to her and enjoyed the emotional and sexual labor she provided--her personality, her character, and her soul mean nothing to him. Ergo, when she's not in top-model form because she's birthed his f-ing children and doesn't have as much energy to spend on him any more, his "love" evaporates.

TLDR: Women take longer than men to fall in love because we actually know what love is, men fall in love quicker because they don't and are misidentifying lust or ego-boosting as love.