Tristan noticed that there's been a difference in Bella's character these past few days. He wanted to talk to her about it but he didn't know how she would take it. She might find it offensive that he is talking about the way she has been behaving.

He has also been thinking of how to make their relationship official so that they can get married though he wasn't sure about Bella's feelings towards him. Sometimes she gives him this kind of mixed signal where she acts like she likes him and there are sometimes she behaves like he's just a friend so he didn't know if she really had feelings...