Open Mouth- Insert Foot

I am afraid I've crossed line with a friend that may have caused permanent damage to our relationship.
My first offense: She went out of her way to get a job for me that isn't going to work out for various reasons. I spent one day on the job training with her, and that same afternoon was offered a position with higher pay, better hours and a more relaxed office setting. I'm going to have to turn down the position she worked so hard to get for me, and although this is a common occurrence in professional settings I am afraid it is becoming personal because of how hard she worked to get me into this job. I am afraid she thinks that I am being ungrateful or that I used her for her connections. I appreciate how hard she worked to get this job, especially because I needed money so bad and she knew that. She was doing me a HUGE favor and I am so thankful. But my priorities right now are money and the plain and simple fact is that I need to do whatever I can to make as much of it as possible.
My second offense: On the way to said job I was teasing her about her boyfriend. He is really competitive and opinionated and can sometimes rub me the wrong way, but nothing that I can't handle. In fact, I enjoy being around him because he challenges me. But I should know by now NEVER to say anything negative to someone about their boyfriend/girlfriend, even in jest. They will always take it the wrong way. I kept teasing her and by the time I realized I had really upset her it was too late. She kept me at arms length the entire day and I could tell that she had been offended by what I said.

I don't know what to do to make things better. This is a friendship worth holding onto. Suggestions?