Guide to having your first threesome, from finding a third to establishing sex boundaries

• Threesomes are a common sexual fantasy, with over 95% of men and 87% of women fantasizing about them, research suggests.
• You should establish safe sex boundaries with your partner before having a threesome, sex therapists say.
• If you are single, ask yourself what your boundaries are before approaching a couple to have sex.

Threesomes are one of the most common sexual fantasies people can have, according to research conducted by Kinsey Institute sex researcher, Dr. Justin Lehmiller.

But acting on that desire is a different story.

A 2017 study found only 18% of men and 10% of women have had a threesome in their lifetime. Lehmiller said this is related to the lack of information available on how to have group sex.

Here is a basic checklist you should run through before embarking on a threesome with your partner or with another couple, according to a sex therapist.

Experiment with dirty talk and video threesomes first

Dr. Joe Kort, founder and clinical director of The Center for Relationship and Sexual Health, told Insider group sex requires preparation.

Here are some questions to ask yourself before agreeing to a threesome:

• Am I doing this for me, or am I doing it for my partner?
• Am I really OK with what we're about to do?
• Do I feel comfortable saying I want to stop, or I want something different?
• Is there anything that's uncomfortable for me that I need to say before we do this?

"Make sure that you tell your partner you're completely happy with them and this is not about being dissatisfied with them, but more about wanting to add to the already great sex life you have together," Kort added.

Experimenting with dirty talk about threesomes and video sex with a third partner can help you test the waters and see how comfortable you are with the concept of group sex as a couple.

Single people can find threesome partners on dating apps

If you're single and looking for like-minded people to have a threesome with, Kort suggests online dating.

Tinder, Bumble, and Grindr can all be spaces to find couples looking for a third, just be sure to meet with them in a public place to discuss your boundaries first.

While friends might seem like a more comfortable option, Kort said having a threesome with people you know could harm your friendship.

Partnered people should establish safe sex boundaries before having a threesome

Kort told Insider you should have a conversation about safe sex practices, like using protection and any possible sexual boundaries you have, before meeting with your third. Non-monogamy-focused apps, like Feeld, 3Somer, and 3Fun, cater specifically to people looking for group sex.

"Each one makes a list of all the things they want and then you agree on a mutual vision based on the two lists," Kort said. "For example, the list might include sex acts that get a green light from both of you, ones that are a maybe, and ones that are a definite no."

Once you two are on the same page, you can meet with your threesome partner for coffee and exchange your boundaries.

Vet your threesome partners before having sex with them

Regardless of whether you're single or partnered, Kort recommends meeting with threesome partners before sex.

"Meet for drinks or coffee in a social public place so that you can get a feel for each other and talk about what's going to occur and what the boundaries are for all of you," Kort told Insider.

After you meet, you and your partner should have an honest conversation about how you both felt about the person. If everyone is on the same page, then you can proceed.

If you are single, you should ask yourself how comfortable you felt with the couple after you meet them in a public place.

Feeling guilt or jealousy is normal

If you feel guilty after having your threesome, you shouldn't panic. According to Vort, we are trained from childhood to be monogamous so trying non-monogamy in any form can come with a lot of remorse.

Feeling jealousy towards your partner is also natural due to this programming.

"We are trained from childhood to be monogamous, and we are going against long historical scripts," Vort said.