Alex had taken what Claire said the day before very seriously. He wanted to understand it all more fully so he spent most of last night looking things up about facial expressions, body language, and compassion/sympathy.
So when she was obviously upset about the car bomb incident he wanted to make her feel better. A sort of heaviness filled his chest when she said she needed to be alone when they got back to her house. He had wanted them to do something fun again today after spending so many hours repetitively patrolling the area around her workplace.
It took him a while to figure out why she was acting like this but then he remembered how freaked out she had been by the car bomb. She had barely been in control enough to remember to call the police.
Claire was afraid again. It didn't seem to be of Alex this time, which was good, but he still didn't like it. He far preferred her when she was happy.