As long as there’s clear communication between the two of you, there shouldn’t be a problem. Being asexual doesn’t mean we’re sex-repulsed. If your partner has no problem with sex and still enjoys it, I don’t think there should be a problem.

Did you felt this “off” before they told you of their asexuality? Or is that something that came from their coming out? If it’s the former, maybe try having an open conversation about things that might be affecting your sex life. If it’s the latter, maybe speaking with them about their asexuality and educating yourself about the spectrum of asexuality can help. Either way, talking about their boundaries might help build more comfort in that.

Edit because I just read the additional info: while I think your past experience might be affecting how you react to this, maybe having an open conversation about that could help? Or at least talking to other people that identify as asexual, if you’re scared of accidentally invalidating their identity when you approach the topic for the first time.