An attitude of gratitude is the basis for most strong relationships. Research shows that expressing gratitude for one another has major impacts on the overall strength of your partnership. “Gratitude is important, and expressing [it] helps your partner know what it is about them that you appreciate, respect, [and] value,” Nicole Richardson, LPC-S, LMFT-S, licensed marriage and family therapist, tells Romper. “It is important even to yourself [that] you consider and focus on what you admire about your partner.” I mean, have you ever resented someone for being too thankful and appreciative of your efforts? Of course not.

In order to thrive, relationships have to exist in reality. That means you deal with difficult truths as they arise. “Freedom to openly communicate means that problems can be solved and worked through,” Richardson says. “Happy couples that stay together have conflict… Being able to speak your mind to your partner is just as important on good days as it is on the bad days.” Everything from political leanings to hot dog condiment preferences is fair game.

How do you and your significant other react when things go right in life? Offering enthusiastic support for your partner when they get a promotion, finish graduate school, or even survive a difficult dentist appointment is important, according to 2004 research in the Journal of Personality and Social Psychology. “Couples who celebrate each other’s wins are more satisfied in their relationship,” Anita Chlipala, licensed marriage and family therapist, tells Romper. “Doing so shows that your partner validates you, believes in you and what you are capable of, supports you, and will continue to encourage you.” Sharing in one another's triumphs tends to produce happier relationships overall.

Laughter can help defuse even the most emotional conflicts, and according to Chlipala, laughing with your partner can increase intimacy. “Having a similar sense of humor is helpful because it allows you to join on something that can add joy or levity to a situation,” explains Richardson. “That isn't to say you have think all the same things are funny. It can be hurtful if one person gets offended by the other person's sense of humor.” So careful with those seemingly harmless jokes. But if you can laugh about almost anything, then your relationship will be much more pleasant and grounding.

Sure, it's said in pretty much every relationship article ever. But couples who have good communication skills — who are open, honest, and respectful — tend to last. “Communication is probably the most important part of any relationship,” notes Richardson. “Even our pets communicate with us, though they do it nonverbally. Communication is about being heard, seen, and valued. There are times the communication lifts us up and makes us feel giddy, and there are times when it makes us uncomfortable; both are equally important to the health and longevity of the relationship.” Communicating openly with your partner, and not expecting them to be a mind-reader, is a fantastic sign. Sometimes you have to spell it all out, and that's OK.

Destiny's Child said it best: "You know I'm not gon' diss you on the internet / 'Cause my mama taught me better than that." Using social media respectfully, and refraining from blasting your dirty laundry all over Facebook, is the sign of a strong relationship. “The Golden Rule is totally applicable here,” offers Richardson. “If you wouldn't want your partner to post something hurtful or embarrassing about you, then it's not a good idea for you to do it either.” Sure, those argumentative, public posts between couples are entertaining for the rest of the internet, but they can be pretty destructive for the couples themselves. Disagreeing privately is more respectful, and a sign that you both truly value each other and your relationship.

Are you and your partner on the same page about marriage, kids, and where to live? Great. Sharing basic life goals and values is the foundation of a lasting relationship. It means you're both pulling together in the same direction. “Not all goals need to be shared, but they need to be symbiotic,” explains Richardson. “For example, if one partner dreams of staying at home one day with the kids, and the other partner is cool with that, great. If not, it's something that needs to get looked at and explored further. Think about how you want to live and [whether] each of your goals support that into the future.”

In general, people in a healthy relationship accept one another as they are. It's a good sign if, say, you don't expect your freewheeling, artsy partner to straighten up and get a CPA license one day. “It is disrespectful to tell someone they need to change in order to suit you,” says Richardson. “There can be habits you can ask for (like putting clothes away), but expecting someone to adopt your worldview or change their appearance to make you happy is unfair. If you truly love someone, you have to love their smooth parts as well as their rough edges. Don't forget you have flaws too, and you want to be loved as you are.”

Don't underestimate the importance of joy in a relationship. “Fun and playfulness are cornerstones of friendship and flirting,” notes Richardson. “It's really important to just focus on the things that aren't perfect in relationships as well as life. Every problem cannot be solved in one conversation. It's OK to set things aside sometimes and enjoy life.” After all, who wants to be super serious all the time? That's bound to get boring.

Sometimes your partner wants a patient listener instead of someone to offer advice. In these cases, being empathetic with your partner's struggles is the sign of a strong partnership. “You and your partner are growing and changing with every day and life experience,” Richardson says. “Being curious, asking questions, [and] imagining what it is like in your partner's shoes is a vital part of connection, as it allows you to know and understand your partner on a much deeper level.” You can listen without trying to “fix” anything, simply letting them know you’re there no matter what.

Making your entire life revolve around your SO can be draining. Instead, maintaining your friends and hobbies outside the relationship is healthy. “You had a full life before you met your partner, as did they,” Richardson tells Romper. “It's important to nurture yourself by maintaining friendships, engaging in meaningful hobbies, and developing your skills in order to be the best you you can be. We have to love ourselves well to be loved well.” It's important for your own mental stability, plus it gives you something new to talk about with your partner.

People in strong relationships know they can lean on each other. “Your partner is the first one you turn to with good or bad news, hopes and fears,” relationship expert Susan Winter tells Romper. “They are your rock, your best friend, and you know they have your back. They are your best ally and greatest advocate.”

One of the major signs you should not break up is if it’s hard to picture your life without them. There will always be ups and downs in a long-term relationship, but you know it’s worth it if you see them as your future. “Thoughts of a future without your partner [will] feel empty and bleak,” explains Winter. “Having this particular person in your life makes everything better, from the most mundane chores to the greatest life challenges.”

Strong, lasting relationships are also friendships — best friendships. And your best friend will know you to your core. “Times when you feel lost or confused, they know how to ground you and help you find the center of yourself again,” explains Winter. “They know you inside out and can speak to you in a way that kickstarts a positive mindset.”