"For her part, she admits flirting with him beforehand, allowing him to kiss her, "
If monogamy is important to you, dtmfa. This is not the behavior of someone who was forced into douchbaggery behavior. She took advantage of his absence with a total stranger, not like she was romantically inclined.
If monogamy isn't important, shrug it off as a fun tryst, ask if he can join her the next time, and shrug it off. Isn't polygamy great! For comparison's sake, I'd be giving my Girlfriend a High Five at this point, although the STI's might suck.
If monogamy is important to you, dtmfa. This is not the behavior of someone who was forced into douchbaggery behavior. She took advantage of his absence with a total stranger, not like she was romantically inclined.
If monogamy isn't important, shrug it off as a fun tryst, ask if he can join her the next time, and shrug it off. Isn't polygamy great! For comparison's sake, I'd be giving my Girlfriend a High Five at this point, although the STI's might suck.