[Harmony♥]

It depends.

I think that if both parties are consenting that it's okay for either one, or both, to date other people or multiple people at once, it's no big deal. If one doesn't know of the other's dating other people, then that could be considered as cheating, I suppose.

It all depends on the situation, and what both parties had agreed too.

Open relationships also mean friends with benefits, so I'm not sure sleeping with multiple people is cool; I mean, your having sex with one person, then those two people are also having sex with one or more people. It just leads up to bad reputations, possible pregnancies (where one doesn't know who the father is) and STD's if you don't know if the other is clean. It could be fun for a while, but dangerous as well.