She's likely scared. All of a sudden, he's developing a connection with someone that she hadn't expected. She probably thought that it would happen more slowly or not be as deep as her own. Plus, new relationship energy is really scary when you're the one being left behind. Some people don't know how to handle it so that the primary isn't left feeling like they're not desired.
I doubt it's any comfort or help, but we went through this when we first started. Asha asked me not to be alone with Sunday, or spend time bonding. I was kind of going through similar issues about the feelings between her and Easy, so I went along with it, and of course it didn't last long. Only long enough for her to figure out that (Sunday + me - Asha) was not a viable equation.
I'm sorry things didn't work out for you. Of course you know you can post here if you need some emotional support.