I'm not attracted to him. I'm dating him. I'm a bi guy.
Okay, but don't you think it's wrong to date someone you're not attracted to?
Because I'm hungry for dopamine, there is no other explanation.
You should not be dating someone you are not attracted to. If you do not like this person you should break up so they can move on.
I can't do that, it will hurt his self-esteem.
It may be better to hurt his feelings temporarily than make him hurt more in the future by keeping him seem you're interested with him even if you're not. It is going to be more hurtful to him to know you have been lying for a long time, so I suggest that you should be more honest sooner than later.