I understand how you feel, Patraman. My gf of four years truly loved me, but we were very different in our lifestyles and our goals and the way we looked at others, the way we looked at the world.
But what happens is you get lazy, and it's so easy to go on; you both know deep down it can't last forever, yet you let it slide, day after day. And the older you get, the harder dating and finding a new companion becomes. She was 47, me 49.
In the end, I had to admit that it wasn't going to work, as much as we both wanted it to. But I had to give it a chance, because in many ways we were very happy with one another, we connected so well.
I think those are the relationships that drag on so long after they should end; the codependency thing where you are both comfortable, but not fulfilled.
Anyway here we are and now we have to figure out how to go forward. Dealing with the loneliness and the guilt over hurting her is very hard. And I think we have to guard against the mistake of running to someone new too soon, just to have companionship.
Sounds like you have family and friends and you are very lucky. My children live away from me, my parents are dead; and I recently had to move to a new city. So I am pretty isolated.