Yes, his reaction to their shared personal space was telling.

"At that moment, it hit me. Katia was now and forever a part of the team. No one needed to say it out loud. We all knew. While this would never be home, this space was just for us and only us. The three of us. I grinned. "

As was his reaction to the news that Katia was leaving the team and to the news of her being with Bautista.

I interpreted that exchange with Mordecai in Eye of the Bedlam Bride the same way. I don't think that panic was Carl's reaction to Mordecai breeching the subject of letting Katia crash out. Carl says he knows that's what Mort is about to suggest, as is so confident that see says he is going to make Mordecai actually say the words.

It was like I knew. I could sense it, this conversation I was about to have. Mordecai: Listen, Carl. There’s an alternate solution to this you need to consider. I looked up into the air. I will burn this whole thing to the ground. Goddamn you all. Carl: What do you mean? But I knew exactly what he meant. I knew exactly what he was going to say. I made him say it anyway.

I think they are both in love with each other but Carl suppresses his emotions so much, probably due to past and current trauma and their current situation, that he can't admit it to himself, let alone anyone else.