What do you do when your follower melts down or cannot follow a pitch?

I've used a 3:1 several times to help my partner up. The key work is help. You'll never actually pull them up, like if they were unconscious or on an overhanging route, but as long as they make some attempt at upward movement, a 3:1 will help them up. If they're less than 1/3 of a rope length away, the drop loop method is extremely useful as well.