I don’t get what’s wrong. To me, he’s the best thing that’s ever happened. So...why? Why does she continue to play me like this?

My boyfriend and I got together on November the 22nd; our 100 day anniversary is soon, March the 2nd, very soon. I trust him, he trusts me, we have a steady relationship. My best friend, we’ll call her “Mary” and we’ll call my boyfriend, “Alex”. So Mary, who broke up with her boyfriend a month ago keeps bugging me about one thing. She keeps saying,

“June, I think you should break up with Alex.”
And whenever I ask her why she says the same things, “He’s a bad influence on you. You don’t love him, you only think you do. You can’t love someone you don’t hang around. Your relationship with him now is literally a thin thread that can break in any moment. He’s going to cheat on you or break up with you and you’re going to be heartbroken. I’m doing this for you, June. It’s for the best.”

Which I would respond with, “You can’t tell what I’m thinking, how are you so sure that I don’t love him? How do you know our relationship status? How would you know if he would break up with me? How is this for the best?”

Our ‘best friend status’ seemed to be wavering more than my ‘relationship status’. She didn’t quit at it. Even after our fights, I would forgive her and give her another chance. But, she continued to try and try and try. One day, she told me, “Oh my god, come on, it’s getting old.”
That made me furious, “’Getting old’? Are you trying to tell me, you want me to break up with Alex and get with another guy because you think it’s ‘getting old’?!”

These few weeks, I’ve been cold towards her. She doesn’t even realize that I’m mad and she would even ask me, “Are you mad at me?”
We were texting each other when I started getting mad at her and she finally said, “What’s your problem?”

I chuckled at my iPod screen and said, “What’s YOUR problem?”

“I don’t have a problem.” She said, “You do.”

“You’re so dense.” I said and then signed off.

The next morning, when she saw me she asked, “Are you mad at me?”

I smiled, “No, what are you talking about? Why would I be mad at you?”
“Okay good.” She said and we were the normal best friends again. To her at least. I kept myself on the edge and reminded myself not to trust her anymore. I stopped being the cheerful soul around her and instead I took everything from her seriously.

I told Alex about it and he didn’t really seem to mind as much as me. But he did get mad at Mary. Whenever Mary brought up the subject about breaking up with Alex, I would listen to her thoughts then brush them aside like mosquitoes. I never realized that my best friend was like this and even now, she continues to try.

Why do you do it, Mary? It can’t be just some sudden urge to bring me down. You’re doing this on purpose. After all, you’re the one who told me from the beginning that my relationship with Alex would be s***. I respected your all your relationships but guess what? My kindness towards you, it’s getting old.