What was in his notebook and some other questions...

I am not sure if I got that part right, she opened his notebook and saw an image of them holding hands on the viaduct, I assume that was supposed to mean he was planning for them to die together as she said she wanted them to. Was that really so easy to figure out from the drawing?

If I got this right, why was he planning on them to die together? It didn't seem he was ever even one bit into the idea before and I also wonder how much he even loved her (being gay and all)? Why would he be planning that? Especially before the whole mess happened when she killed the guy he was into?

Also, how come he got so attracted to her after she killed his friend? Was he in love with her, confused?

Another kind of silly question, why did he kiss that girl in the restaurant? I just don't see his reasoning there.