Leo's are always right: what to do?

Me (sun: cap, moon:cancer, venus: sag) and my coworker leo (moon: taurus, venus: virgo) kind of got into a fwb relationship (only third base). A few weeks ago he told me that it'd be better if we just stayed friends. He explained later that he was sorry and doesn't love me but does like me a lot and didn't want to hurt me because he was afraid that I'd fall in love with him. I didn't quite believe I would because I don't fall in love that fast and often, but I did. I think I can live with staying friends and I think he can too, but I'm not sure if I'd ruin it if I tell him because in general he thinks we're just friends. It wouldn't be awkward if we'd end our fwb, we'll stay friends for sure. But perhaps if I tell him he'll feel different about me. It's 99.9% sure that we wont get into a relationship because he doesn't want to with someone he doesn't love at fist sight and our interests are miles apart. The things we do have in common is our sense of humour and our mindset.
I'm going abroad for a month so I wont see him in a while. I'm in doubt if I want to tell him before I leave, when I'm back, or not at all. Would he understand/get over it? Or would he feel awkward when I tell him? (It's funny because the first time we hung out together outside of work he told me he could never stay just friend with a girl. I told him that I'd be the exception to that. Turns out I'm not. Leo's are always right.)

Awkward, yes.

Very.

Sorry. 😢