This has been answered here and there, but given the size of the thread, can be tough to find. I know @Sashira has addressed this before.
The easiest answer…it depends. Some of it will depend on the species itself, and what they prize, and of course individuals within the species will have different views.
The following is just my take, and what I remember.
A good example are the demons. Given how they must feed, it is pretty much accepted they will date with multiple partners (and this doesn’t include ‘one-night stands’). By the same token, staying monogamous, or as close to it as they go, might generate more controversy since it impacts the health of their partner.
With vampires, it would be accepted as well. In fact, one of the choices for a vampire player to pick is their “parent’s partner” to feed from. So it seems vampires will occasionally get into a very intimate relationship with someone, especially if they feed from.
It would be less accepting among goblins, since they seem to be preoccupied with their fertility as a species, and anything that takes away from it can be a problem.
Werewolves actually seem to be a conservative bunch as well, though I chalk that up more to pack dynamics and instinct as well.
Wendigo are just to few to really have a big consensus on this. There might be some wendigo who are like ‘don’t play with your food’ but there would be others who are like ‘it’s a tough existence and if it helps you get through it.’ It really depends on how human the wendigo in question is.