Over the course of a relationship, you’ll likely encounter complex and difficult emotions, from jealousy to grief to shame. All sorts of feelings can test a couple’s bond, but one of the more stealth yet destructive emotions is resentment.

“Resentment in a relationship can be toxic and harmful if left unaddressed,” Damona Hoffman, host of The Dates & Mates Podcast, told HuffPost. “It often builds up over time when one or both partners feel hurt, ignored or misunderstood.”

Often in relationships, there’s resentment around unequal division of labor or feeling unappreciated.

“It can begin to occur due to imbalances in your relationship, such as one partner carrying more of the mental load, whether it’s pressure to manage parenting, financial or domestic responsibilities,” said Samantha Burns, a couples therapist and relationship coach.

Resentment can manifest in subtle ways that aren’t always super apparent to your partner – or even to yourself. HuffPost asked Hoffman, Burns and other experts to share some of the sneaky signs of resentment in relationships.

“Pay attention to shifts in communication and in how you express yourselves and react to one another,” said Tracy Ross, a licensed clinical social worker specialising in couples and family therapy. “Is there more sarcasm, more edginess or a negative tone?”

Take a look at what might be happening beneath the surface if you detect changes in the tone, frequency or style of your communication with your partner.

“Signs of resentment can be insidious and small verbal and nonverbal behaviours, such eye-rolling, sighing, criticising, a general lack of respect or value for your partner’s opinions or actions, and invalidation that overtime builds up and overtakes many of your interactions,” Burns said.

Passive-aggressive comments, subtle digs, scoffing and belittling what the other person says can all point to resentment. There could be a sense of moodiness or short closed-end statements that cut off actual conversation as well.

“Partners harbouring resentment may start keeping track of each other’s mistakes or past wrongdoings, using them as ammunition in future conflicts,” Hoffman said.

Sometimes this score-keeping is unspoken, while in other situations it might be more explicitly expressed.

“Someone might be bringing up past grievances frequently, focusing on tit-for-tat,” said Mabel Yiu, a marriage and family therapist and founding director of Women’s Therapy Institute.

There might also be a sense of tracking who is contributing more to keeping things running smoothly or working harder.

“You might feel as if you constantly have to sacrifice your own wants and needs,” said April Henry, a licensed marriage and family therapy associate at Millennial Life Counseling. “You lack empathy for them or their excuses.”

“It’s healthy for couples to have their own interests and friends they see separately, but if one or both partners seem to be finding excuses to avoid another or get out of spending solo time together, that’s a big red flag,” Hoffman said.

Ask yourself if you’re feeling withdrawn or emotionally disconnected from your partner. Maybe you aren’t interacting as much as you used to.

“Are you avoiding certain conversations or spending time together? Are you making excuses for being less available?” Ross said.

“According to Dr. John Gottman, criticism is one of the biggest signs of trouble in a relationship,” Hoffman explained.

Indeed, his “four horsemen” of a relationship apocalypse are criticism, contempt, defensiveness and stonewalling.

“Are you feeling more critical of your partner’s family, close friends, work situation – and do you find yourself judging, complaining or nitpicking – or vice versa?” Ross asked. “Do you find yourself feeling superior – ‘what is wrong with him/her? I would never do something like that.’ Do you feel contemptuous instead of mildly annoyed when your partner is late, or doesn’t clean up, or any number of small things?”

Take note if the way you deal with conflict and differences has shifted to a more critical approach.

“Another sign of resentment is blaming – making the other person the scapegoat for their unhappiness,” Yiu said.

In addition to frequently nitpicking or complaining to your partner about things they do, a sign of resentment might involve how you talk about your partner to other people.

“Do you find yourself complaining behind your partner’s back, assuming the worst instead of the best of a particular miscommunication or conflict?” Ross said.

A little venting to your friends here and there is fine, but pay attention if it starts to feel excessive. Are you only talking about your partner as though they’re a terrible person?

“Oftentimes when someone is resentful in a relationship, they may have less empathy for their partner,” said Rachel Needle, a licensed psychologist and co-director of Modern Sex Therapy Institutes.

“Resentment is clever in the way it masks itself as anger,” Henry said. “You may think you’re upset with your partner for not unloading the dishwasher, but soon realize the gradual build-up of unmet expectations has actually turned to resentment. Resentment may have crept its way into your relationship if you find yourself in a continuous loop of feeling increasingly irritable around them.”

Resentment can manifest in emotional outbursts or cold behaviour as those pent-up feelings are released. Resist the urge to boil these deeper issues down to pure anger or sadness.

“You may find an increase of conflict about small things that always seem to come back to a larger past issue, feelings of disgust and disdain and feelings of overwhelm and high stress,” said Alysha Jeney, a relationship therapist and founder of Modern Love Counselling.

“Oftentimes resentment is a reaction of being overly stressed – being in the fight, flight or freeze part of our nervous system – for an extended period of time and not knowing how to come back to the parasympathetic nervous system of rest and digest. We feel exhausted, stressed and need help, but sometimes don’t know how to get it.”

This can make us more easily angered or annoyed by our partners. We may even villainise them because we don’t feel seen, heard or supported, which could activate inner wounds from our past.

“You might begin to assume that your partner is intentionally trying to anger, annoy or upset you, instead of giving them the benefit of the doubt – which leads to you interacting defensively and perpetuating the negative dynamic,” Burns said.

“Resentment can affect physical and emotional intimacy, causing a decline in affection, sex, and emotional connection,” Hoffman said. “I find that couples who get to the point of resentment have actually had a slowing or lack of intimacy for months or even years.”

One or both of you might pull away both emotionally and physically and show less interest in intimacy.

“Ask, are you less interested in sex, affection, being close?” Ross said. “And of course all of this can be true in the reverse as well. Maybe you notice what you’re getting from your partner doesn’t feel quite the same – less tolerance, more distance, less connecting, less prioritising one another.”

Whether you’re experiencing a sense of physical and emotional distance, increased criticism or a temptation to keep score, just remember that resentment does not have to mean the end of a relationship.

“If you detect resentment in your relationship, talk about it as soon as possible,” Needle urged. “As soon as you sense an issue, communicate about it rather than let something fester or an issue go unresolved.”

In addition to fostering healthy communication, she recommended working on forgiveness, gratitude, compassion and finding a middle ground to deal with resentment. If resentment continues to affect your relationship, seek the help of a mental health professional.