Your concern for your partner's well-being is what keeps you from holding off a break up. Picture: PxHere

How many times have you heard "He's not right for you" or "why do you keep on letting her treat you this way"? 

Ending a relationship that you know is bad for you takes a great amount of strength. Yet some of us just can't seem to let things go. Why is that so?

Scientists think they may have the answer, and, it has something to do with altruism.

Even when you are not completely satisfied in your relationship, your concern for your partner's well-being is what keeps you from holding off a break up.

"When people perceived that the partner was highly committed to the relationship they were less likely to initiate a break up," lead author Samantha Joel told Science Alert.

Joel studies decision making in romantic relationships at Western University in Ontario, Canada.

"This is true even for people who weren't really committed to the relationship themselves or who were personally unsatisfied with the relationship. Generally, we don't want to hurt our partners and we care about what they want," she said.

Her findings support a growing body of research that shows human behaviour is inherently prosocial - behavior that is intended to benefit others.