How do you do it?

For background: together 20+years. Kids are either grown or close to it. SO and I used to do everything together (stupid stuff like errands but their love language is quality time). That has quit entirely. They have someone else that they do these random things with. No its not a cheating scenario, im specifically being vague. If i went into more detail it would no longer be anonymous.

On top of that, trying to deal with empty nest syndrome. Kids are off doing their own thing and I dont feel like I have a partner anymore. I try so hard to be chill about it to be honest, Im struggling. I have talked to them and told them how I feel and he says he gets it but then he tells me to just come with them. Why feels counterproductive.

Is this normal? How do you deal with it? Before anyone tells me to get hobbies and friends. I have my own hobbies and my friends all have SO and kids. Im not location somewhere where its easy to meet new people. And he takes multiple trips a year without me so there's that.

tl;dr empty nest and absent spouse is slowly driving me crazy.