Hot Girl Tells Me She Has A Boyfriend... Then Asks Me Out Immediately Afterwards

Will women cheat on their boyfriend when another guy comes along? According to Rollo Tomassi, author of The Rational Male, the principle of hypergamy dictates that women have an instinctual drive to cheat whenever they meet a higher-status guy.
Whether the principle of hypergamy is real is an interesting debate, however, I have had a number of experiences where women expressed a willingness to cheat on their boyfriend, fiance, or even husband within minutes of meeting me. This girl I met from daygame asks me for my number immediately after asking for her number.