Some advice I gave to a friend earlier today:
"Love is like a garden - it has to be tended to thrive."
What's that mean? It means all the little acts that keep a garden alive - a bit of weeding, watering, ensuring plants have the support they need - are similar to the things that keep relationships thriving, like time together, acts of kindness, gratitude, etc.
Nature provides the seed, but it's nurture that helps it grow.