I support this notion on the backing that the only reason humans tend to cheat, is because the partner they cheated on is not what they were looking for although they ended up together. There is always something missing from the pair. Making the original quest of finding a "soul mate" much more difficult. The fact of the matter is, one should never cheat, reason being if the thought of cheating ever comes up and IS a valid possibility then that couple does NOT belong together.
So with this reasoning, I say humans are fully capable of monogamous relationships. Making it by nature, natural for humans.
Monogamy is learned and unfortunately not very well. We are taught the a committed relationship should be one man, one woman and exclusive. We are supposed to use our brains, and morals and stay true to one person, and one person only. However, our "nature" is to cheat or have multiple partners.
No, I don't believe humans as a whole are monogamous by nature. I believe women are probably monogamous by nature, but it is different for men. Through evolutionary biology, men have acquired different partners and it has become part of their biology. Men are not necessarily wired to be monogamous.
I don't think that we are monogamous by nature. Most apes are not monogamous either. Many humans find it difficult to stay faithful in long term relationships even if they love their partners very much. I don't think it is our natural tendency to want to stay with one person, but we have the capability to if we choose.
If people want monogamy that should be up to them and their agreements. If a couple wants to allow an open relationship it's nobody's business. If a bunch of people want a relationship that's nobody's business either. We don't need any shoulds about how to form our relationships other than communication and mutual respect.