He says that he doesn't want to engage in a relationship just yet because he gets obsessed with things and he "wants to give you his UNDIVIDED attention". The implication of something permanent is there constantly. So, while he does not outright say this there he later says "Can scarcely imagine to be without you now." There is this constant looming that it is serious for him - which it might be - but then it gets pulled back.

These are the options I can see:

1. Shitty writing
2. Serious commitment issues
3. Manipulating emotions
4. Lack of player agency