How do I tell my boy-best friend that his girlfriend doesn't actually like him and just feels bad for him?

I've been friends with this guy for a while. I just recently found out his girlfriend, Kyara, (also one of my best friends) whom he started dating yesterday is only dating him because she feels bad for him that he gets rejected a lot and couldn't say no.

How do I let him down easy?

I also ACTUALLY have feelings for him, so another option is for me to tell Kyara to tell him the truth, tell him I like him, and have him ask me out instead. He doesn't really have a type, so he might like me.

What option is better?

How do I tell my boy-best friend that his girlfriend doesn't actually like him and just feels bad for him?
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