I'm up to 90,000 words. I've written most/all the major scenes, I basically have exposition and links left, and then the first draft is ready. Then I'll edit/tighten etc - the first 5,000 or so need a major rewrite. However, I am approaching the point the book is finished.
The main characters have become like friends. I watch and learn about them. What the book is about isn't what I thought it was when I started.
Writing at lunch time I had a major revelation (in a minor way). Rich and Lizzie are still desperately in love, even after 30 years together. I know I described them this way, but as I type I don't have to write it - I just put down what I observe. They met when Lizzie's best mate said to Rich "My mate fancies you, will you ask her to the Christmas disco" when they were 5th formers (year 10).
As I wrote I found their relationship is the rock on which the others depend. The book is actually about Gabriel and Lucy, with a minor theme of Charlie and Jason. But with out Rich and Lizzie the others, especially Gabe, couldn't do what they do, they act as a fixed point. And with in that the outgoing Lizzie relies on the calm Rich to be the centre of her universe.
Sometimes I go to write one thing and a character will say something totally unexpected.
And one day, in a few months, I'm going to stop learning about them.
Do the job in front of you.