That is why I don't play with humans. I just use the computer generated players in a four player game.
The problem with that is that computer generated players and the game over all is so poorly written in terms of computer game programming, that it really is a tough game to play without getting horribly frustrated.
On more than one occasion, my bot partner has gone out instead of picking up a card off the discard pile that would have formed a canasta.
It gets even worse.
If the opponents are going to win the game, the computer generated partner should not be trying to go out, it should be trying to form more canastas in an effort to have an even higher score before any player goes out.