This comes to mind
"If you love something, set it free. If it comes back it was always yours, if it doesn't, it never was."
A bit sad but very true.
If you have lost contact with friends and aren't very sociable, he could be feeling the pressure of being your everything, if that makes sense. Then he goes out on NYE, on his own and then you get jealous about it, even though you had to work.
Maybe, he just needs to feel that he can go out without worrying that it might upset you. I'm speaking from experience, and DP used to feel like that when I had lost touch with people and hardly went out.
I think the best thing you can do is make contact with friends again or even arrangements with some work colleagues and go out and enjoy yourself without him. I think I used to be quite suffocating without meaning to be. I had massive insecurity issues and was always very clingy but didn't actually realise this unil DP and I talked. He then old me that it worried him that I was so reliant on him. I've always been very independent but had o admit that he was right.
I love my DP very much, but he is no longer my be all and end all, if tha makes sense.
If you can, let him have some head space while he decides what he wants. In the meantime, get out and start getting our friends back as they really are important. And show him that you're having fun without him. I don't have any fiends for lots of reasons to do with things that happened before I met DP, and I think that was the root of my problem. It made me focus more on him than was healthy I think. I didn't really start to feel better or recognise this until I started taking antidepressants as I was really not happy within myself, if that makes sense.
Sorry if this is a rambling post. Some of what you said reminded you of me a few years ago.
Take care and remember, whatever happens will be for the best. xxx