It's an evolutionary thing. Men have evolved to impregnate women to keep women theirs. They do not want males to come in the way of them and their women. They run the risk of cuckoldry if this happens. Thats why some violent male partners unconsciously beat their female counterparts because they want to beat the other man's child out of her and terminate it so he can impregnate her himself.
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It's weird that a guy wants a woman to be PREGNANT. but nonetheless, maybe he would just like to have kids, a kin to feel as though he still belong in this world? I don't know :o it's rlly complex. haha
It just means he loves her truly, and you don't have to be married because you have children, that's totally optional for the soon to be parents. My parents didn't really get married and they turned out fine LOL
So in the end, it really depends on how they want to define their relationship if they decide to have a baby
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