"Sometimes it's what they don't say," says couples therapist and relationship expert Tracy K. Ross, LCSW. "You don't have a clear understanding of why the relationship ended, what wasn't working for them, how the breakup occurred, and whether or not they have any contact, [or] they make a point of not mentioning their [ex’s] name."

If you feel like your partner is always vague when the subject of their ex is raised, there may be a reason why they aren't telling you the whole truth. Withholding information can be a big red flag, especially if you've asked your S.O. to talk about their past relationship and they've still avoided the topic.

If your partner seems either "too interested or uncomfortable when their ex's name comes up in conversation, either when you are with others or when you're alone," that could be a red flag, says Ross.

One troubling sign to take note of when your partner talks or hears about their ex is if they look physically uncomfortable or upset, according to relationship expert Emily Holmes Hahn.

“Someone who's able to maintain open body language, a positive tone of voice, and objective opinions during this conversation is usually someone no longer looking in the rearview mirror,” Holmes Hahn previously told Elite Daily. “It's also someone who wants to show you that they were ready to commit in the past and are not suppressing any dark secrets about their romantic history."

Trying to play something off like it isn't a big deal often means it is. Especially if your partner's most recent relationship was pretty serious, the way they react to mention of their ex can reveal a lot about how they truly feel.

This includes making subtle comparisons as well as blatant comparisons, according to Ross. They might also "mention qualities in their ex that you clearly don't have," she says. Drawing parallels between you and an ex isn't a great sign. Your boyfriend or girlfriend should love and respect you for who you are, not for how similar or different you are to their ex.

"If you have a feeling you are the rebound person or aren't sure what it is about you they really like or value, pay attention to that," says Ross. "Your significant other should bring out the best in you."

If you feel like your partner idealizes their ex in specific ways, such as saying, "They were the best at this," or "The one thing I do miss is..." that could mean there is "a sense of nostalgia where their ex is concerned," says Ross.

They might also "talk about activities they miss that clearly involve their ex, even if they don't reference them directly," she adds. This behavior could be an indicator that your partner is still hung up on their last relationship.

Keeping photos of their ex on their phone might also be a sign that they are not fully over the previous relationship. "The frequent reminders of the person ... keep us from mourning the loss of the relationship," clinical psychologist Dr. Joshua Klapow, Ph.D., previously explained to Elite Daily. "The result is being stuck in between being with them and moving forward."

Other signs to look out for include if "they are overly critical of their ex, you still feel the anger when they talk about them, or they become emotional — angry, sad, etc. — when their [ex's] name is mentioned," says Ross.

While opening up about being hurt in a previous relationship isn’t necessarily a red flag — if anything, it could be a sign that your partner is emotionally intelligent and stable enough to talk about it openly — it’s important to keep in mind that past traumas can still affect the present.

"If your partner talks about being blindsided in some way by their ex, either by the breakup or a revelation, you should beware there may be some residual effect," Ross says. Even if this doesn’t spell doom for your relationship, it might mean you have some things to work through as a couple.

If your partner goes out of their way to stay in contact with their ex's friends and family and justifies this contact if you question it, they may still be connected to their ex, according to Ross.

Maintaining mutual friendships is one thing, but if your partner seems overly invested in their ex's social circles or even goes as far as putting themselves in situations where they're likely to run into their ex, you might want to talk to your S.O. about their intentions.

"Pay attention to your internal compass," says Ross. "If something makes you uncomfortable, doesn't feel right, or causes you to question, don't ignore it — address it."

Aside from simply talking about their exes in an unhealthy way, there are also some red flags to look out for that might mean your partner's past relationships were unhealthy in general. If "your partner talks about how [they were] wronged by the ex, how they were a victim, [or if they give] examples of how they weren't treated well, and the angle is blaming the ex [rather than] questioning why they put up with that kind of relationship," that should be on your radar, Ross says.

When "it's all criticism of the ex and no responsibility on their part, no nuances — black and white thinking," that's not a healthy way to deal with a breakup — and maybe they aren't yet ready to be in a new relationship. "You should beware of falling into and repeating the same patterns [as in past relationships]," says Ross. "Listen to what they are telling you, and if possible, have an honest conversation about what the hook was in that unhealthy relationship."

Talking about past relationships can provide you with important information about your partner's needs, patterns, blindspots, and connection style, both healthy and unhealthy. If you ever feel uncomfortable about the way your S.O. talks about an ex, don't be afraid to initiate a productive conversation. The sooner you get it out in the open, the easier it will be to let the past go and focus on building a strong future together.

Experts:

Tracy K. Ross, LCSW, couples therapist and relationship expert

Emily Holmes Hahn, relationship expert

Dr. Joshua Klapow, Ph.D., licensed clinical psychologist