How should I break the ice politely? Or should I just stay quiet?

i have this friend who really likes a girl who i think is sort of out of his reach AND she's already dating someone but he's like literally IN LOVE with her. he keeps talking about her and asking me about her, and he finds the littlest coincidences to say things like we're soulmates and stuff like that. honestly, i don't mind him doing this but it's gotten to this sort of "hopeless" point and being around him is getting draining (probably because he ignores me when i try to politely tell him that the person he likes is dating someone). i don't really know if i should be fr with him or not because i cherish our friendship and i don't want him to be heartbroken, so please gimme some adice :(