For the most part, I am a big fan of open communication between partners. If you’re in a serious relationship with someone, you want them to know a lot about you—the good and the bad. You want to be open enough that they can understand and love the true you. In most areas, being as transparent as possible leads to a stronger, closer relationship.

But there are a couple of exceptions. Your partner may think he wants to know everything about your past, but there are some things that no one really ought to know. Countless times I’ve had someone sitting in my therapy office say something like “I really pushed him/her to tell me because I just had to know, and now I can’t get that image out of my head.” It’s actually beneficial to your relationship to stay mum on a few topics.

Don’t tell:

Positive things about past partners’ bodies. If your past boyfriend had six-pack abs, or your past girlfriend was stacked, your current partner does not want to know that. He or she may say she wants to know, may even ask for a detailed description—but do not give one. No good can come of it. Most people, even the buff and beautiful, worry about our bodies’ imperfections. The last thing you want is to be canoodling with your sweetie and have him/her start worrying about his/her body comparing unfavorably with someone from your past. That’s a total buzz-kill—no fun for either of you.

So what can you say? If your former partner was, in fact, very attractive, try not to mention the fact at all. Because what would be the point? If your current partner has met the past partner or seen pictures, knows the ex was hot, and comments on that, there’s no point in denying it. But don’t dwell on it. “Yes, she was pretty, but so are you, and you’re a much better fit for me because ________.” Your honey may press you on this: “She’s so much prettier than I am.” Don’t bite. “C’mon, she was pretty, but you’re beautiful/the one I’m in love with/so much better for me. I’d much rather talk about all the good things we have going on.”

Too much detail about sexual experiences with past partners. On one level, your partner may be fascinated or aroused about stories of things you’ve done in the past. But there is a real risk that images from these stories may stick in his mind in a negative way.

Exception: If you’re in an ongoing relationship, it is wise to tell your current partner if you had a deeply negative sexual experience in the past. Here the details would be less about the experience itself and more about its effect on you. That way your partner can be extra cautious or supportive around a sensitive area.

Anything that would embarrass a past partner. Sex is powerful and intimate. Most of what goes on in the bedroom is not the business of anyone who wasn’t there—not even of the person you now love. Honor your past partners by respecting their privacy, as you would hope they respect yours. Your current partner should appreciate that you treat people so respectfully.

Anything untrue. This “don’t” isn’t about protecting someone else—it’s about protecting your relationship by not over-protecting yourself.

You may wish you had fewer partners, or more. You may wish you had tales of exciting sexual exploits. You may wish you’d never had that hook-up with that horrible person. You may wish you hadn’t played around so much when you were younger.

The wishing is fine, but telling what isn’t true is not. Even small lies/fudges/untruths in this area can do huge damage to your relationship when the truth eventually comes out (as it always does). It is a thousand times better to be up-front from the beginning. If it’s early in the relationship and you don’t feel ready to tell something, be honest and say you don’t feel ready. But don’t lie. The fact that you lied would be far more damaging to the relationship than the truth, no matter how unpleasant.

The past is part of your story, but what really matters is how you treat one another in the present.