Thanks for posting!! While that chair does look like a cozy place to curl up for a nap, I see how it could throw a big brown wrench into your design plans!
In this circumstance, when the item can’t be removed from the design or the room, we’re left with no choice but to design around it. That chair isn’t the most becoming on its own, but throw on a cute throw pillow that aligns it more with your color scheme and a nice blanket draped across the back and the impact is mightily lessened. Your boyfriend can’t really complain about a pillow or a blanket since he brought in an entire, big chair!
If a blue couch is in your dream design, I would encourage you to still go for it! The brown, while not in your color palette, is still a neutral, and won’t throw things off as much as, say, a lime green chair would.
Keep the rest of the room in your color palette, help the chair out with those accessories, and I promise your living room will still be on point!