Human relationships are quite intricate and fragile. It takes a lot of physical, emotional and spiritual energy to sustain. At some point, the whole endeavour seems futile and unimportant. But as you said, love is the most beautiful thing.
I have experienced growth in character through love. I know what it means to be patient with someone who often you don't get to see eye-to-eye on so many subjects. I have learnt how to be firm and flexible simultaneous.
For me, conflict resolution is probably the most important part of a relationship. How do we handle each other when things hit the fan? Can we find our way back to ourselves when we are torn apart? Many people never get to answer these questions until it's too late.