God’s plan for those who marry is to stay happily in love for life! Whatever else ‘staying happily married for life’ takes, I know of two foundational things it requires:
Being faithful to keep your marriage vows.
Being intentional to grow your marriage relationship.
For those wanting to nail down the first idea more firmly, let me suggest buying the classic, “Horton Hatches the Egg”. Read it together and afterwards, repeat these words to one another, “I said what I meant and I meant what I said, ‘I will be faithful to you 100%”.
Another suggestion is to find the vows you said to one another at your wedding and say them again to each other.
For those wanting to enhance the second idea, here are some suggestions: