If they are mainly one sided, they never work.
Sure, at first if one person is putting more effort into the relationship it may not seem to be that big of a deal. However, it’s that old adage “standing the test of time” that comes into play. When a relationship is unbalanced as far as investment of time, effort, and emotional energy it is not sustainable.
In every relationship there will be times when it is 50/50 and both partners/friends/family are fully engaged. Then, there will be other times it is 70/30, and most likely there will be a time when it is 100/0. Perhaps you or the other person in the relationship is struggling and doing all he/she can just to survive their own “stuff.” But that 100/0 is not the aim . . .
One of our ultimate goals should be to aim for the 50/50 mark.
How do we do that?
Actually, it is quite simple.
We hear clearly the teachings of Jesus.

The Greatest Commandment

34 Hearing that Jesus had silenced the Sadducees, the Pharisees got together. 35 One of them, an expert in the law, tested him with this question: 36 “Teacher, which is the greatest commandment in the Law?”37 Jesus replied: “‘Love the Lord your God with all your heart and with all your soul and with all your mind.’[c] 38 This is the first and greatest commandment. 39 And the second is like it: ‘Love your neighbor as yourself.’[d] 40 All the Law and the Prophets hang on these two commandments.”

We need to love others as we love ourselves. That is often times easy when we are “serving” within the boundaries of a faith community. “Giving and serving” feels good. We are living like Jesus, right?

BUT – It is not as easy when we are in a day to day, hour by hour relationship with someone.
Yet we must look at others and see their needs first, over and above what we “want” to give . . . then we are living into the Great Commandment. That is also how we build healthy, strong faith based relationships.
We are called to love ourselves and try to ensure our own needs are met. However, there is a next step. That next step is to take our focus off ourselves and tend to those around us. To care about and serve those that we love.