Illusion? no. it is a choice between partners and without even going into what my stance is on it, yes it is possible to have that with another person. It is not unreasonable to want that at all but you have to find a like minded and commited partner to have that.

The part that bothers me more is not that people feel the need to have multiple partners. I know there are plenty of people that want that but the problem that exists is not in open relationships where people agree to this but where monogamy is assumed and expected and one partner chooses to have other partners in spite of being in what is assumed to be a monogamous relationship.

If two people want to have multiple partners, both know about it and accept it, I don't have a reason to judge them.

I believe that part of the reason people do cheat isn't always so much that they need multiple partners but for so many reasons other than that. One thing, typical in a chronic cheater is taht I think they get a high off of doing something in the dark, that is, leading a double life.

Monogamy is real, it is possible and it is not an illusion. Dont' give up on taht for a few untrustworthy partners.