Imagine having for 9 months an abomination in your guts. Imagine a foreign body, a worm. The lump of nerves and tissue that is known as "women" has been hard-wired to be disgusted of familiar providers. What is more, it is also hard-wired to take advantage of them. Because, if they can submit her to that ultimate insult, i.e. impregnate her with a monster, what behavior can match that insult? Oh, she'd better get everything she can, while she can, out of him, to make up for the possible damage - and to gain, if possible.  The whole female existence is defined by those, ...well, existential issues.