One of the ways i like to explain it (which now is termed compersion) is that you’re so into a person you can enjoy seeing them enjoy someone else and that you feel so secure its just sexy to see them be sexy and makes you want them even more.
Its an adoration of a person and wanting to see...
She’s got to feel fully confident that she owns you and you’re going nowhere. And you can’t fake that. If she gains that confidence, IMO, then its something you can explore