Question: how to know if a relationship will fail?
Answer: A rescuer/rescued relationship. Either side of this may feel good – at first. ... 
Avoidance of difficult issues. ... 
Gradually cutting off your other relationships. ... 
Trust issues and unjust suspicions. ... 
Unresolved prior relationship. ... 
No interest in your kids. ... 
Over-involvement with family of origin. ... 
Financial inequity.