It wasn’t until after I’d been in a relationship with my fiancee for a while that I realized I’m polyamorous. I’ve talked to her about it and she says she’s at least willing to consider the idea, but I don’t know what I should do if she decides she wants a monogamous relationship. It just feels like an unnatural state of things for me, but I don’t want to force her to change how she thinks… I’m just really torn and anxious. What do I do?

What you do is don’t smash those eggs before they hatch! If she says she’s willing to consider the idea, pursue that first. Be receptive, patient, and gentle, but stay optimistic. You two may be able to work something out! Don’t freak out over a projected worst-case scenario until you find yourself in that scenario - which, right now, you’re not. Try to stop your mental wheels from spinning around in that dusty rut and focus instead on your partner and where you two are right now. Wait to see whether your fears come true before you start worrying about how to face them.

Poly/mono incompatibility is a tough spot to be in, but it’s a reality for some people. One of life’s most frustrating truths is that sometimes people are sexually incompatible in ways that compromise and communication can’t resolve. A woman who is attracted to a gay man will need to accept that there’s no scenario in which she gets what she wants, for example. If you two absolutely can’t work out some terms on which you’re both happy and fulfilled - if she says she absolutely demands 100% monogamy, and you absolutely won’t accept those terms, the relationship is toast. Dan Savage calls it the “price of admission” - if monogamy really is the price of admission for a relationship with this person, you either need to be willing to pay that price, or accept that you won’t be admitted.

But don’t let your anxiety drive you into a conclusion that isn’t yet foregone. It is entirely possible that your fiance will find herself surprised by how comfortable she is with polyamory. Or, you two might work out a compromise where both of you feel happy and supported. Focus on that as your end goal before you start worrying about how to deal with a bad situation you aren’t actually in yet.