Any success stories?

At that point in the relationship, when I read posts I can relate, when I read the replies I get frustrated. I guess there isn't really any easy answers. Any success stories or when you get to that cliff is it going to happen sooner or later? Rationally the right thing to do is stay together. Seems like the other part of the brain wants to run and keeps saying life is too short to be bored and miserable. Tried a psychologists didn't make progress in the few times I saw her.

Does that person who motivates you, works with you exist? Is a soulmate a myth?

Some details -
The good:
No infidelity and ok sex life
Have young kids who we adore
Together over 15 years without big problems
Both have been trying to make things better but we are both giving up

The bad:
Starting to struggle financially
Both began hanging out with other people and we both seem to get more enjoyment out of that but are bored when we go out together
Major issues with in-laws
Disagreements on raising kids
Starting to fight over minor things
We used to tell each other everything, now we both withhold information about feelings, inlaws, etc
On my end, feels like I'm trying to do the right thing, but can't find happiness