Dating advice

I would like to know if the person I’m dating is seeing other people but I’m afraid to ask. I assumed he’s only dating me but I know that’s just me justifying not asking because I find it awkward and scary.
I originally wanted to do this several months ago, but I posted for feedback here and I didn’t like my reason for asking so I never did.
I decided to wait and see if I wanted a future with him before asking. Well, now I’ve fallen in love and the thought of him dating other people is devastating.
I tried asking once and I didn’t go through with it because I know if he tells me he’s seeing other people then I would end the relationship. Any advice is welcome. I originally joined SCS for biz coaching so I’m still working on applying it to dating.