- Relationship compatibility may not sound very sexy as a subject, but it is the key principle that determines whether your relationship will be a lifetime of love and laughter or destructive disaster. And why is relationship compatibility so important? Because the relationships that lack of it breaks up. A few relationships break up because of violence or abuse, but the majority end because the couple were just not compatible. It’s the biggest issue because a lack of compatibility means you’re wasting your time trying to work out what’s going wrong with the deeper dynamics in your relationship.