Descriptions of former flames should be kept short and sweet, avoiding examples that might make your current partner feel inferior, Morse said. Never compare, she warned, or use exes manipulatively.
"No 'Well, my ex always came with me to my work functions, why won't you?'" she said. "That just makes a person feel bad."
Timing is everything
Any talk of exes, except in the most general terms, should be avoided in the first several dates, Morse said, as people are most insecure in those early stages, and it should be a time to set a foundation for the budding couple.
Morse has been on plenty of dates that have violated that basic wisdom.
One guy picked her up for a first date and started bashing his ex-girlfriend while they were still in the car on the way to the sushi restaurant.
Another guy told her, on date two, that he used to have a lot of threesomes with his ex-girlfriend, who then left him for his best friend.
"My mind goes into, 'Why are you telling me this? Are you into threesomes?'" Morse said. She ended the relationship after a few more dates because, she said, "I would always think about it."
Morse advises against discussing sexual history at all, except to confirm sexual health such as STDs. People have a masochistic proclivity to ask how many previous sexual partners there have been, almost always to see how they measure up, but "you cannot win with this conversation," said Morse, so she recommends keeping numbers out of it.
If faced with that question, Morse suggests you say it's not relevant and gently steer the talk to what you love about your current sex life.
Navigating conversations about past relationships gets trickier when one partner is particularly curious and the other particularly private.
The rule to live by in such circumstances is that your job in a relationship is to make your partner feel secure. So if partners want to know, tell them, and if they don't want to know, don't, said clinical psychologist David Wexler, executive director of the Relationship Training Institute in San Diego and author of "When Good Men Behave Badly" (New Harbinger Publications).
The person requesting the information should control how much is revealed, within reason, Wexler said. Compromise may be necessary so both partners feel respected. The partner being interrogated should draw boundaries if the questioning becomes obsessive or intrusive, and take care not to divulge details that may do more harm than good.
This requires some finesse. Talking too glowingly about a former lover can make it seem you're still attached, while being too critical or embittered toward an ex suggests you haven't healed or that you're easy to hurt or disappoint, Wexler said.
Honesty is a must, but that doesn't mean you should open the floodgates.
Wexler described one client who revealed to his wife that he once had a major porn addiction. Though his confession began as an act of respect, it morphed into getting his misdeeds off his chest while she cried "TMI!"
"Unless you've gotten some clear signal that he or she really wants to know all these things about your past, there is no reason to plant unnecessary doubts based on who you used to be," Wexler said.
When your ex is still your friend
Talking about exes is sticky enough. How do you handle it when you or your partner remains friends with an ex?
Be fully transparent about your friendship with the ex, and include your current partner in plans with him or her, said Emily Morse, a sex and relationship expert who has remained friends with several exes. There can be no secrets here, just reassurance to your current partner that you are no longer in love with the ex.
Don't forbid your partner from communicating with or seeing an ex, unless there has been a blatant betrayal or injury, said clinical psychologist David Wexler. Exerting such control creates resentment and is a vote of no confidence, which eats away at the relationship. The safer way to address it is to state that you are uncomfortable with the friendship and let the other person take steps to make you feel more secure.
Rethink if it's such a good idea. The sexual tension tends to remain, and men — in particular — connect sex and closeness, so it can be difficult for them to be just friends, said Reginald Richardson, vice president for clinical services at the Family Institute at Northwestern University. If you are spending time with the old relationship to the detriment of the new relationship, that's a problem.