Yeah, the answer to every situation that we wouldn't personally tolerate is not 'low self esteem! she's a fool!'. We don't know what they've agreed to. She appears to be well aware of the dynamic and not bothered by it so...there it is.

I get off on other women flirting with my DH, but I'm a freak in many ways.

I don't mind when girls try to hit on my boyfriend or find him attractive. It's flattering to me that other women want what I have and they won't get and I am secure in our relationship. But, my boyfriend never has and will not entertain these women's flirtations. He politely excuses himself or tells them he has a girlfriend. I laugh it off and tease him about it.