Mother Nature seems to find our higher-order mental and emotional processes annoying or amusing. She just wants us doing it. Chemistry, biology, whatever. Her agenda isn't ours, but sometimes they can coincide, as in this case where Jack was able to provide what you most needed in the moment.

I can't do hookups, not because they wouldn't work for me, but because I can't help feeling something for someone when I've been in bed with them, and I don't want to feel attached to someone I don't like or trust.