Everyone in a relationship knows how easy it is to accuse a partner of something they didn't do. It's their fault, you tell them, whether the spat is about towels on the bathroom floor, an angry mother-in-law or a missed restaurant reservation.

Sometimes you know you're wrong the second these words leave your mouth; other times you recognize your mistake in the days to come.

But the same people often miss a much more critical aspect of their relationship, despite repeated examples and gut feelings that something is wrong. It's far more difficult to realize that your partner may actually be at fault when you suffer from mental health issues.

"Some have the power to uplift our spirits, to lend comfort during life's strains and stresses, to weave fun and playfulness into our day, and to imbue life with a profound sense of purpose," psychologist and Harvard lecturer Holly Parker, author of "If We're Together, Why Do I Feel So Alone?," told Bustle. "Sadly, others can pull us downward, drain our energy and emotional reserves, fill us with heartache and erode our happiness."

Some of these woeful partners contribute to a condition, like depression, that may have already been present. Others push a person with relatively strong mental health into a rapid decline.

In both situations, it's all too easy to miss the signals. Bustle writer Suzannah Weiss, for example, started obsessive hair picking (trichotillomania), had trouble concentrating on work and wasted lots of time watching television for a good while before she realized an emotionally abusive partner was the root cause of her mental anguish.

You owe it to yourself to figure out if you're having a toxic reaction to a relationship, psychologist Andrea Bonior told Health.

"Keeping a finger on your own emotions can help you develop insight about the people in your life, so you can choose healthier situations," she said.

And while each person has to weigh a relationship's worth for themselves, there are common signs that indicate a partner's actions are hurting your mental health:

Your self-esteem is slipping. If you can honestly say you were more confident and felt better about yourself before this relationship got going, your partner could be the one lowering your self-esteem, Parker said. The routine might be subtle, like a partner who talks about themselves constantly while asking you very few questions, which can lead you to feel less interesting. (This could also be a symptom that you are in a relationship with one type of narcissist.) Or it could be more obvious, a constant barrage of overt insults that reaches emotional abuse proportions.

"When one of the people you're closest to is making you feel inferior, you may start to believe you are," Weiss noted.

You're always walking on eggshells. A controlling relationship partner can do plenty of damage even without physical threats or violence. "It can simply be that you feel frightened to share your opinions—you're constantly walking on eggshells because you're afraid of your partner's emotional reactions," Bonior noted.

Your physical health has tanked since the relationship started. Sure, it could be a coincidence. But Parker warned that an unhealthy relationship can cause headaches, insomnia or muscle pain. The link to mental health? If one of those physical problems has erupted due to your relationship, it may indicate an underlying mental issue as well.

You're relieved when your partner checks out. Of course you could just be losing interest, but a physical sense of relief when your partner leaves after you've spent substantial time together could indicate your partner's causing you stress. Give this observation even more credit if your relief when your partner departs is accompanied by "a sense of weight and physical tension in the parter's presence," Parker noted.

When it comes to finding a relationship, experts say timing is everything. In fact, Match.com says it now knows the exact date and time when singles are most likely to meet their, well, match online. Oli Kellett/Taxi/Getty Images

Credit: Nedra Rhone

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Credit: Nedra Rhone

You go to great lengths to distract yourself from the relationship. This is a psychological arc: when you are in a relationship with someone, you will make every attempt to avoid negative thoughts about them. When the negativity threatens, it can cause you so much cognitive dissonance you will do anything to push it to the back of your mind. Some of the distraction techniques can wear away mental health, like oversleeping or playing video games for long hours.

Of course, eliminating the relationship is not going to magically erase your mental health problems, but it could have a positive impact. "Although many stressors in life can undermine emotional health, the possible role of relationships should not be dismissed," Parker said. "If a romantic relationship is having a negative impact on your psychological well-being, it's vital to turn attention to that."