I'd be okay if that was allowed.
Where I'm from [The United States] there no rule against having multiple relationships at the same time; having multiple marriages however is... Although, if you meant by the norms of society and not the law, then yeah... a lot of people would not approve. lol
It's quite a struggle for people to be faithful, just let them do what they want and make some babies of all kind.
I agree.. So many relationships end because of infidelity.. Frankly even if I were in a mono relationship, I would want a partner to tell me if they were sleeping with other people.. There are a lot of STDs out there and as such knowing the sexual patterns of a partner is necessary. A partner who refuses to use condoms provides difficulties in an open relationship.