Are lasting, truly monogamous relationships still realistic today?

I wish to believe that relationships can last, and that its not only me who desires for a monogamous relationship. But I see more people indulging in the opposite then anything.

People are either with you cuz they enjoy the variety, the opportunity, whatever you give or provide, etc. Or they are merely settling with you (while admiting so) because they didn't have anything better to chose from.

So many people say that humans are only as faithful as their options. And around me, till now, that has proved to be more realistic then the thought of people actually settling WITH YOU, cuz they actually wanna form with you something long lasting and serious.

Am I maybe too naive and should abandon monogamy to be a realistic expectation? Should I approach relationships for the sake of my own mental health more pragmatically, if I do not wanna get hurt? Or would it be more realistic for people like me in such a cultural climate to remain celibate, if most monogamous people are practically at this point like unicorns?
Are lasting, truly monogamous relationships still realistic today?
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