Wow, what a tough spot to be in.
Without knowing the specifics, I would say the time to bail out, is when one (or both) of you is no longer willing to try.
As long as one of you is willing to try (and the other is amenable to the effort) then there is still hope.
Loveless marraige? That takes time to build, so I’m not sure if you can say you’ve hit empty till you’ve been working at building the realtionship of at least 5 years.
Is the parnasah situation something that needs to be looked at? That might be a sore subject, but one that could be a game-changer.
” Same few things that neither one of us seems to be able to get past”
Again, not sure what this is referring to, but everything (well. almost everything” can be negotiated.
See if you can summarize the “things” into a single sentence per thing (not here, between the 2 of you) and see if you can tackle one point at a time.
Either way, think long and hard before jumping ship. Its a very cold and lonely world out there, and one that does not forgive mistakes. Try to fix your marraige, whatever it takes.