It depends on the type of relationships we are talking about,if the relationship is a relationship 

whereby both partners love each other then the love will make the relationship last long,the 

reasons why they were in the relationship with each other most times will determine what will 

make the relationship to last long,if two people went into a relationship with each other because 

of the friendship they do have then it is the same friendship that will make the relationship to last 

long and when the friendship stops then such relationship will not last long