Best friends 4gasm

Since I first talked about masturbation with my best girlfriend thinks started getting weird, at least in my head. It was more of a joke but she told me that I could masturbate in her room while she was gone somewhere. Then one day, when I asked her if it was okay if I would masturbate before falling asleep, she first told me, that she would put in her earplugs in order to keep sleeping, but then she said that she would like to listen because it might be "funny". She hesitated shortly and said, that it might also arouse her and that she would maybe start masturbating too and that we should not do that.
Often we where talking about sex while I was giving her a massage, that we both where aroused. When I was laying in bed I would secretly start masturbating, hoping that she would be sleeping. Then sometimes I thought I might have heard a noise of something rubbing but then again, I would tell myself that it was just me, and that she was actually asleep. I start paying attention to her breath and all sounds become way more intense. There were many nights where I could not sleep because I would masturbate waiting for her to sleep but on the other hand secretly hoping that she might hear or see it, then coming over and starting to kiss me, or giving me a blowjob or hand job. Then also there were situations where she told me that she started masturbating while talking to me on the telephone, just because she was bored and that she was doing this very frequently some times. Then I heard some vibrator sounds another day from the background of our phonecalll. Another evening nearly had sex when she was drunk and trying to make me aroused.
My fantasy is always, that she sees me masturbating and interacts or, that I see her masturbating and just join her... Maybe we would also start masturbating together but finally becoming so horny, that we would fuck each other very hard. There was also one night where I definitely heard her vibrator and she moaning, while I was masturbating. It's always the same, I never know if she actually did it...