He's perfect for you... but he has an excuse every time you invite him to meet your friends and family. She's everything you've ever wanted in a partner... but she's hyper-critical of all the decisions you make.
It's easy to disregard your reservations when you've found someone who seems perfect for you on paper. But trusting your instincts in the beginning of a relationship could save you a tremendous amount of hurt down the road.
Below, relationship experts offer nine types of people who just aren't marriage material.
1. The flake.
The two of you have so much in common and the chemistry is undeniable. You can't wait until the next date -- whenever that will be; it's damn near impossible to get him to pencil in time for you. The last thing you need is someone who comes in and out of your life but never really commits, said Brenda Della Casa, the author of Cinderella Was a Liar: The Real Reason You Can't Find (or Keep) a Prince.
"They might tell you to be patient or to 'trust' them, but you’re probably feeling more anxiety than butterflies," she said. "You have an instinct for a reason and it’s OK to trust and protect yourself in relationships. Those who want to be with you will make adjustments and those who want to be with you out of convenience will fall by the wayside when you set strong boundaries in place."
2. The too-much-too-soon type.
It's only date number three and you've already been handed a set of keys to her apartment and heard her top five private school choices for your future offspring. That spidey sense you're picking up, telling you to back away slowly from this person? Listen to it, said Amy Van Doran, a New York City-based matchmaker and founder of The Modern Love Club.
"What's the rush here? If it's real, you are not going anywhere. This excitement is less about you, and more about their insecurities and who they are as a person," she said. "It's a red flag when they are too effusive with their words and their actions before they get to know you as a person. The second you share their excitement, the whirlwind has already passed and they are onto their next romantic conquest. Time is the best indicator for who a person actually is."
3. The selfish S.O.
A great romantic partner is generous and willing to indulge the occasional "ugh, today at work..." rant. If you get the sense that the person you're seeing isn't totally supportive, it's a good idea to press pause on the relationship, said dating coach Jeffrey Platts.
"This is really about all forms of giving," he said. "Is he generous with his compliments? Does she listen to you when you're having a rough day? Overall, do you feel that he or she is your absolute biggest fan and cheerleader? And just as important as giving, are they able to pause and fully receive whatever you're giving? If not, what's the point? It takes a healthy self-esteem to openly give or receive an expression of love or support -- and you need that in a partner."
4. The critic.
You can't seem to do or say anything right with this person. Ever. Your theory on what really happened in the "Serial" murder case? Implausible at best. Your unapologetic love for World of Warcraft? A total time-suck. The judgement is incessant -- and in the long-run, who wants to be in a relationship with someone that critical?
"Initially, their stubbornness and convictions might seem attractive -- it's hot when someone knows who they are and what they want," said Julie Nguyen, a matchmaker at The Modern Love Club in New York City. "Those qualities start to turn ugly when you realize there's no room for what you want. These critics demand things to be done a certain way, their way. Real relationships are negotiated by compromise, empathy and the capacity to want to understand where the other person is coming from."
5. The sidekick.
Anything and everything you propose gets the OK, from your plans for the weekend to when you'll move in together. And time apart is virtually non-existent -- you're joined at the hip. You wanted a partner who'd be willing to compromise; not someone who sits on the sidelines and lets you take the lead on every decision, Nguyen said.
"Instead of delving inwards, this type of person intensely picks up your hobbies, follows your passions and does whatever you want to do," she explained. "In the beginning, it's easy and flattering to have someone like you without much effort. However as the relationship progresses, it becomes unfulfilling when you start to realize there's no challenge in the partnership because the other person has nothing else to offer. You need a partner, not a sidekick."
6. The narcissist.
It's my way or the highway with the narcissist. A narcissist can't admit when he or she is wrong and has hissy fits when others try to assert their needs. Clearly, those aren't qualities you're looking for in a long-term partner, Della Casa said.
"This is someone who has the inability to empathize with those around them," she said. "Think about being in a relationship with a narcissist for a minute: Any time you’re hurt, need support or count on them to consider how you might feel -- they won’t be there for you. No real understanding, no sincere apologies, no consideration. That's definitely not the relationship you want."
7. The job hopper.
Don't write someone off simply because they're in the middle of a career change or looking for work after going back to school. But if the person you're seeing is constantly unemployed, getting fired or changing jobs every few months, it may signal a bigger problem, said Della Casa.
"It showcases an inability to make a long-term commitment to something and also gives some insight into their value system," she said. "Whether their movement stems from a sense of entitlement, a lack of self worth or an inability to work well with others, that negative behavior or trait will ultimately find its way into your relationship."
8. The over-reactor.
Arguments and disagreements are bound to happen in any healthy relationship. (It's a good thing, too; you wouldn't have the occasional fight with your partner if you didn't care about the relationship.) That said, you need an S.O. who has the emotional wherewithal to fight fair, not someone who will flip out at the slightest hint of disagreement, Platt said.
"Both partners need to have to the emotional skill of hold space for the other's feelings and perspectives," he said. "It's a big red flag if the person blows up at the first sign of fight and threatens to end the relationship. Our emotional triggers are opportunities to explore our emotions and grow closer, not automatic reasons to question your compatibility or the relationship. The question to ask is: 'Do I feel safe to express myself, even during the heated and stressful moments? And does my partner feel the same?' And if the answer is no, find out why."
9. The lone wolf.
It's essential that you both have lives outside of your relationship. But if you're with someone who's so good on her own, she hints that she doesn't need you in her life, take that as your exit cue, Van Doran said.
"The truth is, a little dependency in a relationship is not a bad thing," she said. "All humans crave connection and a relationship, it's an innate need for people. The overly independent person might say that they want a relationship but won't actually make the space in their life for two people. No matter what, you can't fit in because they won't let you get closer. The more you need... the further you push them away. Ultimately, you don't want to deal with that kind of emotional distance in a relationship."
ALSO ON HUFFPOST:
HuffPost Lifestyle is a daily newsletter that will make you happier and healthier — one email at a time. Learn more