Finn didn't like what Claire Conway had said because he was fairly certain she was right. He had feelings for Carmen that he didn't understand and hadn't realized it until she tried to leave him behind.
He had overheard Alex and Cody talking around 3 AM the other day. About what it means for a person to be important to you. And about family.
If what he had said was correct…Carmen was important to Finn. Alex had said he never wanted to be apart from Claire and that was exactly how he felt about her. He would do anything to stay by her side and see her accomplish her goals.
He cared about her. What a strange concept.
When he came back inside Sarah was trying to make dinner using a recipe she found online and everyone else was looking up what Christmas was and discussing it amongst themselves. Now didn't seem like the best time to try and talk to Carmen. There were too many people around.