This is because — unlike men — women use other women to vet guys. If you have a girlfriend already this makes you much more attractive to many women because it means you’re good enough in some way that one woman chose you. And the higher-status or more attractive the woman you’re with, the more women who become immediately interested.

When I was in the army, zero interest from women. Got a very hot girlfriend and suddenly three different women wanted to hook up with me. Makes no sense.