I cannot deny that FSM may have spoken to you about the joy of multiple sexual partners (for does He not have two stalks and many, many noodles?).
However, I must say it has been revealed to me that FSM really doesn't care one way or the other who (or what) we have sex with, or whether we're having sex with somebody else at the same time, or whether we decide it would be a pretty good idea to only have sex with one specific person, or whether we would like to one day go through the miracle of splitting up the community property with somebody.
FSM would rather leave all that mischief to government, since modern marriage is an unholy institution that creates secure lawyers.
Think of the pastabilities...