I'm for sure no expert on relationships but I like this quote by Barbara Johnson on the importance of unconditional love.
"Never let a problem to be solved become more important than a person to be loved." - Barbara Johnson
Some valuable guidelines for relationships
1. Support the person when you can't support their behavior.
2. Settle accounts immediately - time is the great enemy of reconciliation and restoration
3. Adopt forgiveness when reconciliation is not possible
4. The Bible says that love covers a multitude of sins. Integrate that.
Friends, parents, children, siblings, relatives......need love the most when they deserve it the least.