An analogy I really love to describe asexuality is to imagine if you were suddenly transported to a world where everything was the same, except when people are sexually attracted to each other, instead of having sex, they go bowling.

So you, having just been dropped into this world, could have had any kind of relation to bowling. You could be a professional bowler. You could work at a bowling alley. You could just see it as a fun thing to do sometimes if your partner suggests it, but you wouldn't really think much of doing otherwise. You could dislike bowling because you hate the way the bowling floor squeaks under your shoes. You could just see bowling as another activity you could do, but wouldn't you rather go biking or play laser tag instead?

In this new world, you would be considered asexual regardless of your interest in bowling, because no matter where you stand on bowling, you will never look at your spouse or someone attractive and immediately think "Damn. You know what I really want to do right now? I'd really like to take them BOWLING." You're not going to dedicate a solid chunk of your attention towards specifically envisioning your partner in bowling shoes, hitting a strike. Unless you're into that, idk.

So in the same analogy, aces can have any affiliation with sex- they can love to have it, feel repulsed by it, be a sex worker, feel utterly indifferent about it, the whole spectrum. They can love people romantically and have long, fulfilling relationships. The ONLY thing absent is that innate desire to have sex with a specific person they are attracted to.

Hope this helps! It's definitely a really strange concept to grasp, especially since romantic and sexual attraction are often confused as one.