1. You have to share the same values.
If you have differing opinions on Coldplay or don't agree on why rainbow looms are awesome, you'll probably be OK. But no long-term relationship can survive if you don't agree on things like when to seriously start saving money to buy a home, when to turn off your cell phones and spend time with your families, and whether or not to have kids.
2. Only you can decide what's best for you and your relationship.
Ask your friends and family for advice all you want—and listen to it! They know you and love you—but if your heart is telling you to do the opposite, listen to it.
3. Show your S.O. you care about the things he cares about.
Here's a great rule: if one of you cares about it, it isn't stupid. (Even if it's stupid.)
4. The couples who stay together forever work through the things that could break them up.
No relationship is perfect or without the occasional blow-up, but the couples who stay together for decades and decades are the ones who take the rough times in stride and always prioritize their commitment to each other over fights and hard times.
5. Sex matters.
Sex is a physical way to show the person you love how much you care about them. It's doesn't have to be your number one priority all the time, but neither of you will be happy if you hit the three-year mark and it becomes your last priority all the time.
6. Sometimes when one person's life majorly changes, their values change.
Moving cities for a job or school, losing a parent, or getting a huge promotion at work can change how a person approaches life. If this happens and you find that your values no longer align, it's fine to move on and find someone who is on the same page as you.
7. DON'T SNOOP.
If you're insecure, talk about it. Snooping always backfires. Always!
8. If you spend all your time looking for someone who's exactly like the ex you're still in love with, you'll never find anyone.
At best, you'll get a crummy knockoff of your ex, rather than a unicorn you love for being the unicorn he is.
9. Looks, height, job description, or income bracket won't make someone love you more.
If you refuse to date anyone who doesn't meet a set of criteria, you might find yourself spending more time looking for someone who checks off boxes than someone who adores the hell out of you and makes you really freaking happy.
10. Your relationship doesn't compare to anyone else's.
Your parents had an awful divorce? That doesn't mean your relationship is doomed. That couple you know who seems 10 times more perfect than you and your significant other? Either they're psychopaths who suppress all their feelings in an effort to seem perfect or they fight when you're not looking. Stop comparing!
11. You can't change another person.
People change all the time of their own accord, but never go into a relationship planning to mold the other person to your liking. If someone does change for the sake of a relationship working, it has to come from him, not you.
12. If your relationship makes you feel bad way more than it makes you feel great, end it.
Your relationship isn't always going to be all smiles and cuddles, but if you realize you haven't been having fun or feeling good about yourself the majority of the time, and it stems from your relationship, this isn't the right relationship for you.
13. No one can read your mind.
If you want him to make you dinner on Valentine's Day, you can't say you "don't care" about Valentine's Day and then get upset when he doesn't do anything for you on Valentine's Day. If you need or want something from him, you have to tell him!
14. Communication is the key to solving problems and preventing fights.
Use "I" statements. Don't yell at each other. If you're going to fight, make sure it's productive and you solve the problem so you don't have the same draining fight over and over again.
15. Your relationship is everything.
When you look back at your life, you won't wish you spent more time answering email or looking at Facebook. You'll think about the person you loved and all the amazing things you did together.
This article originally appeared on Cosmopolitan.com. Minor changes have been implemented by Cosmo.ph editors.