Welcome - no, none of that was TMI - we see a lot more explicit stuff on here, believe me!
First, I would advise you to accept how you feel and not try to change anything for the sake of it. If you feel monogamous and only want one person for a long-term relationships, then do that. There are many (including myself) who are in the so-called "mono/poly" relationship configuration - my partner is monogamous, only wants me, but is happy and content with me having others in my life.
So, if you want to try non-monogamy for yourself, feel free to, but don't be disappointed, or think that there is anything inherently wrong if you decide that it's not for you, but you are ok with your partner going ahead with it.
"Listen, or your tongue will make you deaf." - Native American Proverb