Poly isn't the norm, but there are also plenty of awesome people practicing it. There's no reason you can't seek out someone who can give you more time and focus, maybe even a full-time "primary", who would also be ok with your married bf. You CAN have your cake and eat it too! It's just harder and it might take longer to find the right fit.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.