Every day, marriage therapists talk to couples who want to work on making their relationships stronger -- as well as those who check-in as a last ditch-effort to save their marriages. 

What tips them off that a couple may not have what it takes to last? Below, therapists and psychologists share eight of the most glaring red flags.

1.  They have contempt for one another.

Eye-rolling, name-calling and dismissiveness have no place in a healthy relationship. In fact, after four decades of research, psychologist John Gottman has identified contempt -- any statement or non-verbal behavior that belittles your partner -- as the single best single predictor of divorce. 

Becky Whetsone, a marriage and family therapist based in Little Rock, Arkansas, told HuffPost she's seen this scenario play out over and over again with couples she's counseled. 

"I can tell when the end is near when couples start talking badly about each other in front of others or make snide remarks while the other one is right there in the room."

2. One partner has had an affair -- and hasn't worked through the issues that led to the infidelity.

"Once a cheater, always a cheater" isn't always true but it doesn't bode well for a couple if one partner was unfaithful in the past and hasn't figured out why they strayed: What did they feel was missing from their past relationship? Why didn't they vocalize the problems to their partner? We shouldn't be defined by our mistakes, but we should learn from them.

"If either half of a couple has been untrue in the past or in a past relationship, chances are that it may happen again," said Betsy Ross, a Massachusetts-based psychotherapist. "No matter what the reason, having chosen to step over the 'fidelity line' once can make you more likely to do so again when times get tough -- and times always do seem to get tough at a certain point in coupledom, right?"

3. There's a power imbalance.

She just got a job promotion... but her wife is still struggling to find a job since being laid off a year ago. When a couple's sense of equality is compromised, it tends to test the sticking power of the relationship, Whetstone said. 

"Any sort of major power discrepancy between the two -- she's old, he's young; she's educated, he's not; he's rich, she's poor; she's beautiful, he's not -- can end up causing problems in a relationship."

4. They don't look back fondly on the early days of the relationship. 

Couples who are still invested in their relationship love telling their "how we met" story: Even when they're experiencing rocky times in their relationship, they look back on those early days with fondness, said Caroline Madden, a marriage and family therapist and author of How to Go from Soul Mates to Roommates in 10 Easy Steps. 

"In my practice, I ask couples how they met and how they first fell in love: What I'm looking for is any emotional connection to the loving happy couple they once were," she said. "It could be tears, laughter or even anger at why they aren’t still that couple. What that tells me is if there still is a spark between them, that they remember that they were in love and want to be that couple again."

If they can't muster any kind of emotion over their meet-cute story, there's little hope for their future, Madden explained.

"When someone says that they can’t remember or didn’t like something about their partner at the beginning, I know that the couple isn't likely to last. I can rescue couples from the brink of divorce after an affair -- I can’t bring the spark back." 

5. They aren't open and honest with each other. 

As a relationship grows, so should a couple's level of emotional intimacy. If either partner struggles to let their guard down and be open with each other, there's little room for growth, said Antonio Borrello, a Detroit-based psychologist. 

"Feeling that you must hide aspects of your current life is sign of problems with your relationship," he said. "Perhaps you are doing things that are incongruent with your relationship or you have not yet developed enough trust to share with your partner. Either way, when I see this, I suggest that re-evaluating the relationship might be wise." 

6. There are unaddressed addiction issues.

Addiction can chip away at the foundation of even the strongest relationships, said Ross.

"It can be difficult, if not impossible, to remain successfully connected in the presence of the powerful relationship your mate has with his or her substance of choice (drugs, alcohol, food, etc)," she said. "Asking them to get healthy before you commit or say 'I do' is always a good idea and will help you know if they are truly willing and capable of overcoming their issues with substance use."

7. One partner is super secretive about the relationship on social media. 

Let's be real: Couples aren't breakup-bound if they like to keep their private lives private on Facebook. But if one -- or both partners -- posts with the frequency of a Kardashian but doesn't say a peep about the relationship, it raises some serious red flags, Borrello said. 

"Why is the relationship status hidden on social media?" he said. "If your partner avoids posting couple photos of the two of you but is otherwise active on social media, ask about it. Couples who are excited about a future together usually want to share their happiness with friends and family. If that's not happening in your situation, have you asked why? Your partner could be hiding you to maintain the appearance of being unattached."

8. One partner feels alone in the relationship. 

Loneliness is often used as shorthand for the state of being alone -- but the loneliest people are usually those stuck in relationships that no longer serve their emotional needs, Borrello said.

"We all have a need to be loved, accepted, respected and appreciated by another person. When you are in a relationship you definitely expect it. But if those desires are not fulfilled in your relationship, loneliness is often the result," he explained.

True loneliness, he said, is "the feeling we get in our heart when we want intimacy and to be connected with someone, but no one is available or willing to connect. [That kind of] loneliness often leads the other partner to get their emotional intimacy needs met elsewhere."