SS Sorry you are feeling this way. All I can say is you never know exactly what someone else is thinking. She may be thinking about you and your relationship together and maybe she is missing you. She may be also missing the other guy as well but only she knows who or what she is thinking about.
You are the one that has control of your own thoughts. Why not think about something else instead of focusing all your energy on missing her. Of course I am not saying to not think of her at all but maybe just not focus on it so much.
Recently I have found that I have been focusing my thoughts on way to much stuff. I had been letting my mind basically take control and it went rampant thinking crazy thoughts and making me severely depressed.
It wasn't until I took my energy off it and started focusing on something else that things started to change.
~ "Kindness in thought leads to wisdom. Kindness in speech leads to eloquence. Kindness in action leads to love."