It's sometimes very difficult to let go...when you've shared a lot with someone. But people change - every moment of our days brings new experiences that may be very small - they may be large, but the small ones increment and we change. Reliving the pleasant memories in mind doesn't mean you can relive them actually. In fact the intervening divergence suggests you'll never be those same people. You can go to the same places again etc but the experience beyond reminiscence will be different.

Is it not possible just to be friends? Make no more demands of each other? He seems not to want to let go...neither do you, so you'll have to face the pains of that. But deciding you're friends and in non-emotional ways could support each other if needed would seem a way forward.

♀