It wouldn't be your fault if they were upset by your romantic unavailability. That's just like aces feeling guilty because allos want to have sex with them. There's no point. You've committed no crime.
Fair enough; the difference is that there's a wide choice of allosexuals available out there, whereas aces (who're out) are very rare here, so I was afraid that heterorom ace girls might clutch at me like at a straw, lol. My experience shows that my fear is ungrounded, though.
And I thought it might sound insulting to them if I tell them, 'I want to hire you as an accountant, knitter and DnD coach, but I don't want to be your full-time partner, GL with finding one'. Haha.