Can't decide

[Ahoy]

Maybe let him be the one to ask you out for a while. Don't initiate asking.
Also, don't ask questions about how he spends his time. You don't benefit from knowing.
You already know that he's in an A.
Put some healthy distance between yourself and him.
Even though you may enjoy spending time with him, and maybe even enjoy the fact that he is "cheating" on OW by spending time with you, is it worth the emotional energy you spend after the fact trying to figure out what he's thinking.

You said yourself that you are enabling the A.
Sounds like he is cake-eating.
Some people say that he has to think that he might be losing you to feel differently.

Maybe don't make yourself so available to him all the time, as difficult as that may be.

(I am also guilty of jumping to say YES every time H invites me to do something.)

Ask yourself this: Are you detached yet?

If the answer is "No" then it's time to put more energy into being your own person, independent of whatever happens in your R with H, and GAL.