This is just what strikes an outsider with no emotion involved;
You've been together "on and off" for 17 years.
Youve been very up & down (not sure if exact phrase) recently.
Even with being together for the last - years, you don't live together, and presumably no engagement, no shared kids.
Something is clearly not working in this relationship for there to be no consistency and no.commitnent in 17 yrs on and off, and 6 years this time.
Instead of it becoming more stable and secure and committed, you described it as up and down, or whatever the exact phrase was, recently (?)
You say you adore him. Does that mean that all the on & off and the sketchiness has been initiated by him?
It's a good thing you've not had kids by him, because honestly I'd worry you'd have ended up a single Mum.
This way, you have time if you don't fuck around with time, to meet someone else to gave a family with if you want to....and it can be a solid relationship, instead of off/on, up, down, finding out he's cheating etc.