Falling in love is easy. Staying in love requires commitment. When couples say they've "grown apart," it means one or both people have stopped caring and putting in the effort. If you're married, this amounts to a total breach of your vows.
Here are my tips for keeping the love alive:
Value the other person.
When you value someone, you don't hurt them. You don't take them for granted. You are not careless with their feelings. You find ways
every day to let them know that you care.
Listen.
Everybody has hopes and dreams. Everyone gets hurt and scared. Shut up and listen. Don't try to make their feelings go away or tell them how they're wrong. Just listen and hug them. Ask, "Is there anything you'd like me to do?" (which is different from, "Is there anything I can do?").
Apologize and forgive. Whether it's intentional or by accident, you're going to slip up. You need to apologize. Say, "I hurt your feelings by ______, and I realize how bad, wrong, and hurtful it was. I regret it. I'm sorry. I won't do it again." Keep it short and simple, and then live up to your word. By the same token, you also need to forgive. Don't keep bringing something up years later - that's cruel.
Have a sense of humor.
Laughing releases feel-good hormones in the brain and reduces stress. Watch comedies together. Tell each other jokes. Being able to laugh about stupid stuff makes life's nastiness fade away.
Be kind.
Don't make it difficult for someone to be around you. When you feel comfortable together, you're not going to lose each other.
Flirt. Treat your spouse like you did when you were dating. Flirting says you're still crazy about them.
Defend your relationship.
Don't behave in a way which causes mistrust (e.g. addictions, lying, sneaking, misplaced priorities, etc.).