Haven't written anything for some time so here is how it has been and how it is.
L (I'll refer to my girlfriend as L) presented me her point of view and made me realize she did slow down, it calmed me down a lot.
The time when she was in France was full of mood swings for me. Good thing is with every week the intensity of my moods was decreasing (those mood swings were very regular, I had crisis every 7-8 days).
She spent a lot of time with me on chat, which helped me a lot, even when it was just small talk. I need to get some hobby that would occupy me enough not to crave for her attention. I was feeling really uncomfortable demanding so much
Generally I must admit L worked hard on helping me go through this time.
The transition she went through after she had come back was a surprise to me (I should have taken more of my time to go through this forum, now I know it's a usual thing), plus on our first dinner in a restaurant we had a guest that was not really welcome (by me), guess it was my fault not to say explicitly that dinner was special for me.
Now present time.
Finally my thoughts stopped spiraling into anger. I can still get a little jealous about this or that, but I don't have anymore those days when some thought pattern would cause my anger to rise and explode few hours later.
I noticed I have problems not feeling "manly" - lovely society stereotypes, although this is gradually going away, as when I speak with people about my situation, I usually find more understanding and acceptance than I expect. L is helping me fight this feeling too
I wonder how often do men changing their relationship to poly have this feeling.
I managed to accept L's relationship with S but for now I feel rather uncomfortable about opening it further for new partners or casual sex. For now L says that's ok for her, but I hope this feeling passes away and we can progress further.
I still have some problems defining myself. On one hand I know I can love more than one person, I would like a poly relationship for myself, on the other hand I am not uncomfortable being mono, I suppose it's a matter of choice for me. The problem is I'm scared a little of beginning new relationship, I don't know how L would react (she admits there might be some jealousy issues). I am even more afraid of my own actions.
I feel it's unfair she had her time to embrace fully the new relationship during summer, while I could be forced to slow down but would like to enjoy NRE as much. I just didn't get over it yet, so for now I think I'll wait until summer, when L goes to France again and I have more freedom and she has more friends around and her SO. I still have to consult if she agrees with me on this one.
So far I saw no 'profits' for me in opening relationship, but that's not true (my brain tends to be very selective ). We are talking with L more than ever, there is much more emotion between us and generally it feels a lot like a fresh relationship
We are falling in love with each other again. Yay!