I'm glad I don't live on that planet and that none of my girlfriends' boyfriends have a problem with me.

The algorithm here isn't complicated. Ask yourself whether you're someone who can be happily monogamous. If the answer is "no", own up to it, date poly people and have awesome dinners with your new extended family. If the answer is "yes", you have the option of dating somebody who needs your fidelity and offers you theirs in return, and the two of you can live happily ever. And then there are all the other options - but regardless, try to figure it out and be honest with yourself before you get married.