What do you mean by "our," keemosabee? My relatives are human beings. I don't pattern my life on the behavior of primates, particularly regarding the institution of marriage, and I recommend that you don't either.
This is intuitively obvious and proven by common experience.
Uh, if it were so obvious to everybody we wouldn't be debating it, I don't think.
Unless we're lying to ourselves and others.
I think it varies with the individual. Some people prefer the safety and security of a long-term partner, others seek the excitement and variety of different partners, whether through serial monogamy or other arrangements.
I wonder what my wife would think about my seeking "the excitement and variety of different partners." What do you think?
One can be unhealthy with one's sexual behavior, of course, but there are many forms of healthy sexual practice which don't correspond to "one man/one woman till death do them part."
Really? What would they be? And how do you define "healthy" objectively?
Health is the proper operation of the body.
Of course, in all this you've ignored or avoided the central purpose of marriage, which is the begetting and raising of children. Since you've deluded yourself, or are lying to me regarding your true thoughts about children and marriage, please provide the empirical evidence that children raised in broken homes are better off than children raised by their parents.