<human>: Can you provide a brief overview of the text?

My friend of 10+ years [25/F] and a girl [28/F] I used to be friends with (who I stopped talking to upon realizing how toxic she was) share a mutual friend [36/M] with me. He and I are really close to the point where we've been FWB's for almost a year.

He recently told me that both of those girls told him that I'm the type of person who "can only have one friend at a time." He's actually on occasion brought it up and agreed with them. I had no idea they felt this way and I also have no idea what that really means.

I'm wondering if someone can explain it to me and give me advice on how to respond to my friends feeling this way about me. When he brings it up he's saying it negatively and even though I don't understand it, it hurts my feelings. It makes me wonder how my best friend of 10+ years really feels.
<bot>: My friends think I'm the type of person who "can only have one friend at a time." What does this mean and how do I respond to them feeling this way about me?