How do you handle a partner like this?

[umpire99]

This is how it started. Bases loaded with a high hopper down the third base line. F5 knocks the ball down and it goes into foul territory. I am in C. My partner signals fair and all runners move up one base. The visiting coach comes out to talk to my partner. Here is the conversation:

Coach: Wasn't that ball foul when it was touched?
PU: That's his call (pointing to me).
Coach: How is a ball down the line his call when he is in the middle of the field?
PU: No, I meant that was my call. It was a fair ball.
Coach: Where was it when he touched it?
PU: He was in fair territory when he touched.
Coach: I know that, but it doesn't matter where he was. It matters where the ball was.
PU: Then the ball was in fair territory when he touched it. That is a judgement call. Thanks Coach.

Later in the game, the batter hits a dribbler in front of the plate. F1 fields it and tags the runner. There is contact, but I cannot tell from my position if it was malicious. F1's coach comes storming out of the dugout screaming, "You have to get him out of here! He elbowed him!" My partner says something to the coach and then comes out to talk to me. He asks me if I saw malicious contact. I tell him that I could not see it from my angle. He says that he did see it and starts to walk away. He gives the ejection mechanic and says that the player is gone. Of course now the visiting coach is unhappy. Here is the conversation:

Coach: Why is he ejected?
PU: He threw an elbow. I have to eject him when it is that obvious.
Coach: Then why didn't you do it right away?
PU: I just wanted to make sure my partner saw the same thing I did.
Coach: Isn't that your judgement call?
PU: Yes it is.
Coach: Then why did you let the coach scream at you about it?
PU: I have to eject him. It's my judgement. It was obvious.

At this point the coach turns to me and says to me, "You know that is wrong." I assure him that I am doing my best to keep the game under control. I didn't want to throw my partner under the bus, but what do I do in this situation?