I gotta say, refusing to have sex except once every two years would be a dealbreaker for me.

As someone with a physical touch love language, that would be devastating.

I would either need my partner to engage with me sexually in some way (doesn't have to be penis in vagina sex) or to let me have a polyamorous relationship.

It's not fair to unilaterally demand one partner give up what is to them a very important side of themselves. Either let them go or find a compromise.