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Would you find this uncomfortable...and how would you confront the feelings?

I am in a relationship with a guy for a few months now - but we had been friends for 2 years before. I was really good friends with his flatmates, one in particular who introduced me to his friendship group (because they lived in the same city as me) - ill call him person A. I only really spoke to two girls in the group. One girl (person B) in particular started to make me feel very uncomfortable, between her and my boyfriend.

I noticed when i started to have relationship problems with my boyfriend, person A could see he was stressed/unhappy - the same flatmate who i got on well with made me feel as if I was no longer welcome around their house - to the point I stopped staying over. At the same time, the same flatmate who I got close with kept previously saying that person B needed a boyfriend...and then kept also saying that her and my boyfriend are really similar and would get on. At first i never thought anything of it, but then things go a bit weird. The girl had met my boyfriend twice, on the first occasion it was friendly and fine, and on the second she shut any conversation about any other guys she was seeing, whilst my boyfriend was there - weird considering thats all she always talks about using tinder and hooking up. She also kept saying how she found my boyfriend was hot (not just once, a few times) after she had met him. Then i noticed she started ignoring me (if id say go for a drink or library), and messaging my boyfriend instead - for favours, and also because she found out from person A my boyfriend was coming to the city where we both live in efforts to hang out with him.
I just got really uncomfortable by the whole scenario, and I was made to feel not good enough for my boyfriend because our relationship was rocky, and that she was somehow better for him then me. I was confident to tell my boyfriend, and when i explained why i felt a bit off he did understand how it looks - he then told me to speak out, but instead he messaged her saying 'dont speak to me again'. I didnt want him to be aggressive...because it will most likely come back to me...but he had already had sent the message.

I just feel so anxious and I didnt want to step on any ones toes - but i would like to clarify and clear the air, particularly with his flatmate. However I dont know if i am right to feel the way I do?