You just have to accept that sometimes part of ranking up in 2v2 random is carrying your teammate. You won't make it to the top if you can't do that. Winning your side isn't enough; you have to win both sides.
I realize that against good players this is impossible. That's why nobody in 2v2 random that's played more than like ten games has some insane 95% win percentage like the top 1v1 players do.