<human>: MY FWB had mentioned that there was this persistent girl who really wanted him. He said he doesn't like her and can't see themselves dating, but he'll "take whatever comes." Now he's confessed that they're seeing each other and are having sex, but he's "not sure about the relationship."

I suspect that the girl is being led on - She doesn't know about me and she definitely doesn't know what he thinks of her. If that girl were my younger sister or friend, I would say 1) sleeping with a guy doesn't make him want to be your boyfriend, 2) you are not his girlfriend until he brings up exclusivity, and if she's serious (which I suspect she is) 3) hold back on having sex. My FWB is honest and respectful to me. I want to tell him to be honest but gentle with her, but I don't think it's appropriate for our casual relationship.

Can you give me the gist of the text in a nutshell?
<bot>: I suspect that my FWB is leading on a younger girl. I want to say something to him so she doesn't get hurt.