It's definitely a biological concept, since that's exactly what happens in nature with monogamous species.
I don't wish to derail this thread, but I am not sure we are a "monogamous species".
I have heard of Love birds and maybe a couple more cases, but am not aware how many monogamous species there are.
I have one relative who comes from a matriarchal society. This kind of society flourished till recently, but only has changed due to some economic reasons (his wife was trying to explain (can't recall details)).
The male was irrelevant, the women maintained the property and the children. They had all the wealth, and the men were only called in for conception. The dad's role in upbringing was usually performed by the maternal uncles. So men were never needed as bread-winners or for protection.
Each year a different man could be called (iirc). There were no emotions attached to the man, and almost no meeting the man after conception. He could drop in to see the child once a month or so.
Another case is where the old people in the community did the child-rearing and the young were not fettered with a relationship. There are other such systems in various parts of India I won't go into. Most of these are getting broken up due to some of those people traveling to metropolitan cities and picking up western (or outside) values.
I personally think monogamy is an awful thing mankind has inflicted on itself, particularly the whole emotional devastation when you find your partner has "cheated". Men and women are sexually attracted to more than one person, and i don't see how they (barring some exceptional cases) can contain their feelings. So all of you are spending your lives containing your emotions/feelings/desires.
The very fact that there are huge divorce rates shows that the institution itself is flawed. By no means does your biology restrict your sexual impulses to just one person. No where does marriage make some biological change in you that makes only one person sexually compatible to you. That would be bad for the race in the case of death of one partner. Nature is concerned with long term survival, not the happiness or sentiments of individual specimens.
Along with many other rules that go against your biology (that society has inflicted on itself) is this rule of monogamy, and the shame associated with the body and with sex. No other species covers itself. Even children hate to cover themselves, esp in warm countries. We have to drill the concept of shame into them.
However,
this institution cannot be broken since humans have managed to attach a huge amount of emotion to it. Plus the fake shame attached to sex and the fake respect/morality attached to celibacy/abstinence. I seriously hope you guys can dig yourself out of this one in a few centuries ... seriously ... I've seen too many people suffer due to this.