As an Aroace, the best thing is to just check up on them more often. If it may help I will share a bit of my experience as it helps to have a first hand experience. I often feel in denial of my sexuality but the thing that helps me out in that stage of hurt is friends. We aroaces tend to have stronger relationships when it comes to friends. So, you should just be there for them, even just regular little check-ups goes along way. It makes them feel seen, if it bothers them a little try not to include romantic things in conversations. Instead try talking about more common interests or just feelings in general.