Exibit 1. When he shared bodies with her, he could always posses her body and take over. But he left her body after his missions and stuff and let her live while he could of possessed her body and have his own life forever.
Exibit 2. He kinda sounded flirty and comfortable around her, and he never harmed her, he only did so because he obeyed his master.
Exibit 3. He took his time, energy and went to help Dan when ALICE asked him. And he went bravely and even though it was very risky and he could of died. But he didn't and saved himself and I think it was ecause it wasnt his body but Alice's so if he would dies so would Alice. He didn't cared much for what would happen to him sense he did die at the end (disappeared).
Exibit 4. At the moment with him and Alice in their mind they were in a romantic looking green grass hil with a gig and calm wind, instead of some random dungeon or scary place.
Exibit 5. He talked softly and gently with her, also was all flirty and explained things very calmly and easy, and also romantically.
Exibit 6. He encouraged her that she will be fine and that the destiny was hers alone and also told everything in a gentle, soft, calm and romantic way.
Exibit 7. He entrusted her Hydranoid, his only bakugan guardian who was appeared to be the second strongest bakugan in the world. And entrusted to her only.
Exibit 8. He disappeared also counts as he sacrificed himself for her. He left her body and let her live on. It was for her life.
Exibit 9. Alice didn't want him to leave, she wanted him to stay she also stated that she needed him. After all that he could of stayed and not leave, but for her he left and let her live on. Let her have her own life.
Exibit 10. He was smiling when disappearing. He was smiling at her. And her expression looked very sad when he left.
Exibit 11. In bakugan New Vestroia Masquerade appeared in her mind, encouraged her to battle Shadow Prove. Also she did so after he encouraged her.
Exibit 12. He also smiled once more after appearing in her mind in season 2.

Now also it would make plenty of sense if they ended up together. A bad and cold hearted guy with a kind and full of heart girl. It would be like Yin n Yang.
And people should really drop it and forget about this stupid Alice IS Masquerade thing already... I explained like a million times already! To tell it here it will be enough to tell that he is still a guy and she is still a girl and that they share only the same body so everything else is there own! And the way they talked to each other reproved much already!

Thank you. U_U