The interplay of influence in a marriage is so subtle that the issue of who wields the power is almost unreasonable. That's part of my point here. There are more ways to exert influence than to lead an army battalion. But macrohistory consists of army battle fronts and politicians. The narration of that history highlights their roles, but that isn't to say in some ultimate sense that's where the power resides.
Love is in a way integral to evolution.
Certainly, love among kin was very likely to evolve. The social organization of the family in which that love congeals is in turn the foundation for larger social organizations in social species such as ours. It follows less directly from the basic logic of natural selection. In our species, males invest in their children. They try to get a sense of which kids are theirs and they invest in them.