Should I be concerned about my boyfriend's female friend?

[Anonymous]

My boyfriend has this friend he avoids hanging out with when i'm present. I noticed his behavior towards her switches up when I'm there vs when I'm not. When I'm not there, I see him being friendly with her but when I am there, he avoids talking to her and becomes super rude. She always following him around like a puppy dog even after the fact but he acts like doesn't care about her at all, is rude to her, and tries to get her to go away. is he doing something to her to make her want to follow him?

[Wise4myage]

Yeah, it sounds like he is being sneaky so keep an eye on him.

[Avicenna]

Yeah, it's very suspicious