Nevermind, I think I found a way! This loops through every sim the Actor knows and checks if they have a relationship bit with them, then prints both names if it does exist. Also if I add the bit to another Sim with another Target, that isn't returned which is exactly what I was hoping for!
Code:
for target in rel_tracker.get_target_sim_infos():
if target.relationship_tracker.has_bit(sim_info.sim_id, relbit):
output(str(target.first_name + " " + target.last_name))
output(str(sim_info.first_name + " " + sim_info.last_name))