Didn't Cuba only legalise gay marriage last year? Also the CCP (which I don't consider to be Leftist but tankies seem to love) only allows hetero couples to adopt and still doesn't allow gay marriage.

You're not going to change my mind. Some auth-left states doing good things doesn't change the fact that authoritarianism is an oppressive system that I think we should leave in the past. The USA occasionally does things that I agree with too, but that doesn't make their government ethical, doesn't excuse the atrocities they've committed, and doesn't make liberal late-stage capitalism a good system to idolise.