How bad of an idea is it to ignore my polyamoury and polyamourous tendencies and pursue a monogamous relationship with someone who wouldn’t really even be open to the idea of a polyamourous relationship?
I can’t tell you for sure - I think that answer differs for different people. If you wrote me “How bad of an idea is it to ignore my love of warm weather and hatred of urban centers to move to Boston for a great job opportunity?” I also wouldn’t really be able to tell you. For some people, the relationship gained is worth the freedom lost; for others, it’s not. You have to figure that out for yourself.
Picture yourself in a variety of different scenarios that might arise, and be realistic and introspective about how you might react. What would you do if you fell for someone else while dating this new person? What would you do if this new person wasn’t at all interested in some hobby or sexual proclivity that you like to share with partners? Etc.
Set aside some time to think about this deeply and clearly, perhaps while meditating or journaling. And remember that while no choice needs to be permanent, you need to commit to it fully when you make it.