Heh, hell with Sven having "growth." Let's review:
1) Sven's a womanizer who sleeps around;
2) Seemingly, he always has;
3) He makes no bones about it and doesn't lie about it;
4) FAYE went after SVEN, not the other way around, knowing exactly who he was;
5) There wasn't a single string attached to their relationship;
6) He was upfront with her with who he was, she was upfront with what she'd tolerate, and they were both on the same page there;
7) She didn't want any manner of relationship with him but just plain hooking up, and told people so; and
He told her at the earliest possible moment he'd slept around.
How many people'd be calling him immature and a user if instead of being poly, he was a hockey player? "Faye, I like playing hockey." "Well, if I catch you around a hockey rink, I'm outta here." "Umm, hey Faye, I played hockey last night." "Then we're through."
Sorry, no sympathy for Faye here. If you demand monogamy, don't hook up - and it WAS a hookup, nothing more - with someone who's openly, admittedly poly. If you do anyway, then make sure you HAVE a committed relationship and you're on the same wavelength. If you don't bother to do that, to the point you tell your friends that the SO's nothing more to you than the ongoing 11 PM booty call, then spare us the "it hurts so much."