My friend Fish helped me see something very telling today...

Fish "so...if he asked you out again today, would you say yes? what would you say?'
Me 'I couldn't go through this again, I'd have to say no'
Fish "why?"
Me "I know how far behind he is than me relationship-wise, I know that he's just not on the same level as me, and I can't wait for him. And I couldn't go through all this again, I just couldn't. Once is enough."

So this makes me realise I'm not so sad about M any more, I'm more sad about what he stood for. For me he stands for the impossible happening, for feeling things I never thought I could feel for anyone. And I realise that's it's not just him I miss, I miss all that he showed me could happen, how wonderful things can be when you just kinda click. I was blind, in a way, to all the reasons why we weren't right for each other and all our differences. That is what love is about, but it's also about everything just being easy. Being able to be yourself without someone judging you. Maybe we were both judging each other, subconsciously and that was what was leaching the life out of our love. Maybe he just saw it before I did and had the guts to do something about it.
I have to try and remember this when I am feeling down...I'm not pining for him, also what he stood for - the ideal. I hope that's easier to deal with!