"Yo _____, you dating _____ or what? Whats the deal with that?" More in the sense of not sure if they are in one. Well you have 2 choices, assume they aren't in a relationship and go balls deep.
Or
Pretend they are in a relationship and have the deep regret for when they aren't in one and you stay awake at night considering that you had a chance but you decided not to act on it/ respect that they are in a relationship.
IMO you have very little to lose by assuming the former.