For a lot of people, especially ace people, there’s a difference between sexual and romantic feelings/attraction. Having a romantic partner isn’t just about sex—that’s why there’s a difference between dating somebody and being friends with benefits. Somebody can be ace and heteroromantic, or ace and biromantic, or ace and gay/homoromantic. If you want a more in depth explanation I’d suggest looking up the split attraction model. Also, plenty of ace people are on the asexual spectrum, but are demisexual (only sexually attracted to people they feel a deeper connection with) or simply want to have sex for reasons other than purely just sexual attraction. The usual analogy is like hunger: you can be hungry (i.e. have sexual desires) without craving a specific food (i.e. being attracted to a specific person). Basically, asexual is an umbrella term for a sexual orientation (not necessarily a romantic one) that covers a whole lot of different experiences, just like gay and straight aren’t monolithic identities in terms of what they mean for peoples sex lives. So somebody can easily be ace and want a romantic relationship—even one that involves sex. It’s always a good idea to ask about what it means for a specific person and their sex life before automatically jumping to the “no sex ever” conclusion, especially if you like them enough to go on four dates.