Yeah, he doesn't trust anyone here to want to open up. Talk about anything he thinks and feels is like letting others see that he's a pretty bitter creature.

"Of course he deserves it! It just pisses me off I hesitated when I could have done it."

True, if his partner dies Garurumon does too, but that wasn't ever crossing his mind. Afterwards he was told then he wasn't feeling true hate there, but Garurumon is in denial about that. Because others telling him what to think and feel really rubs him the wrong way.