So I've been dating this girl for 9 months now, and we have gotten quite serious. We have had our hiccups, along the way, but generally, things have been good.
Whenever there have been problems, they have been because of her closeness to her best friend, who is a guy. They have known each other for 2 years, and he is like a complete AFC. She calls him her brother, but he clearly has feelings for her, since she is seriously good looking.
I eventually put my foot down, and told her that I was not going to tolerate their closeness anymore, as he constantly tries to brainwash her against me, and this one time, when the three of us met, she was spending all her time with him, and I felt alienated and pathetic.
She eventually agreed to maintain a distance from the guy. However, recently, she has been meeting him behind my back. I know, because they have been seen together by some of my friends. She denies it completely and puts the blame on me for not trusting her. On top of that, she is constantly chatting with him, despite my annoyance at this behaviour. Now, I do not know what to do. She has hidden from me in the past as well as she did not want to cause a fight. However, even when I sweetly tell her, that it is alright, you can meet him if you want to, just do not lie to me, she is still hiding their meetings from me.
I do not mean to act needy or beta, but this really hurts, as I have genuine feelings for this girl, and want their to be honesty in our relationship. I would never hide from her, or make a close friend of the opposite gender, as I respect her and our relationship too much. Now, I have reached a point where I do not even mind their closeness, just as long as I can break this cycle of constant lies. Any idea how I should go about this from here? I ideally would not like to break up. By the way, we are both 21, if that helps.