While you don't need to list every health issue you've had, it’s important to keep your partner up to date on things affecting you today, like STIs or mental-health challenges.

"You should share health issues, or issues that may affect having children, or debilitating illnesses that can impair your ability to do certain activities," psychotherapist Tina B. Tessina tells Bustle. "Be real about this. This is not going away, [but] there are things you and your partner can do to make things work better."

If you've cheated on partners in the past, experts recommend sharing this with your current S.O. "It will cause a lot of pain and lead to loss of trust if your partner finds out first from a source other than you," Gonowon says. So go ahead and own it. By taking matters into your own hands, you'll show your partner you take responsibility for your actions, which can help establish trust.

It’s hard to quantify the prevalence of affairs in couples, but of course, cheating does happen. In a survey from Bustle Trends Group last year, 53% of readers reported having been cheated on.

"What I normally tell my clients is that achieving and supporting healthy, strong communication is the most important determinant of the longevity and success of their relationship," Gonowon says. "Part of this involves fostering trust, which you can establish by encouraging an open and safe environment for both of you to be vulnerable with and fully support each other."

Talking about credit scores and student debt isn’t anyone’s idea of a good time, but it's a necessary topic to cover if you want a serious, healthy relationship. According to Business Insider, money is the number one issue couples fight about.

"Your partner is entitled to know if old financial problems — [like] liens, tax issues, unresolved debts, bankruptcy — are liable to haunt your relationship," Tessina says. And vice versa. By being honest with each other, you’ll figure out if you're financially compatible and can create a plan for the future.

If painful moments from your past are still affecting your daily life, it could be worth talking to your partner about. Whatever they may be, "these events will affect your relationship today, especially if you haven’t worked through them in a therapy setting," Tessina says. "Revealing them will allow your partner to support you in overcoming them."

Consider attending couple’s therapy as well, which could help create coping skills for you and support skills for your partner.

As suggested above, there are many benefits to being honest with your partner about a history of mental-health issues, especially if it’s ongoing. "Answer their questions and talk to them about your current treatment plan,” says Dr. Joshua Klapow, clinical psychologist and host of The Kurre and Klapow Show.

For example, are you taking medication? Have you tried therapy? These conversations will better equip them to be a helpful, understanding S.O. "If you are going to be intimate with your partner in any sense, then part of that intimacy is sharing your health, particularly if it is something that you may need them to support you down the road," Klapow says.

Life coach Chelsea Leigh Trescott recommends talking through your last breakup with a current partner. Were there communication issues? Were there deal breakers that ended things? You can work together to avoid making the same mistakes again.

"Plus, it will actually give your significant other something to aspire to," Trescott says. "For example, if you tell your partner that your ex used to never pick up on the small details that mattered to you, [which] made you feel insignificant and overlooked ... it can act as a direction for [them]."

If you overcame something difficult or embarrassing in the past, such as family tiffs or social anxiety, go ahead and let your partner know. "[It] can be helpful information to share," Bennett says. "It gives great insight into your character and proves that you’re capable of personal growth."

Regardless of whether you’re close with your family, consider sharing stories about your upbringing and familial relationships with your partner. It’ll help them understand you, and also how to be supportive. For example, do you have a complicated relationship with a sibling? How did you cope with your parent’s divorce?

In the past year, millions of Americans have experienced the loss of a loved one. Grief is complicated and nonlinear, and will likely resurface in periods or moments of mourning. It might be difficult to talk about, but consider letting them into your grief journey.

“The healing benefits that come from sharing one's grief are related to how community-building and social support is important in the face of any stressor or life transition,” Azadeh Aalai, Ph.D., an adjunct professor at New York University and an assistant professor at Queensborough Community College in New York, told Bustle last month.

There's no hard rule about what you should share with your partner when it comes to exes or your past. Consider how they might react. "Everyone has different triggers in relationships and it’s important to know them, not necessarily test them," Trescott says. If you think your partner would enjoy the story or learn something from it, go forth. But if you reckon it’ll just make them upset — without any benefit to either of you — feel free to keep it quiet.

"You don’t need to share how many partners you’ve had," says Kailen Rosenberg, a matchmaker, life coach, and founder of Love Architects. It’s 100% up to you. There’s nothing to be ashamed of, but frankly, it’s not your current partner’s business.

This could be controversial, but when talking about an ex, "it’s important that you don’t complicate your [current] relationship and chemistry through comparisons," Trescott says. According to a 2016 Associated Press-WE tv poll, 21% of Americans admit to staying friends with an ex, and another 44% stayed on speaking terms. It’s all well and good, just avoid direct comparison.

"You can easily avoid [comparisons] by telling your partner what excites you or simply guiding them in the moment," Trescott says. "Be vocal about your needs without attaching those needs to anyone who isn’t present to fulfill them."