Definitely, in long-term relationships in particular, people forget about kissing. It's like, you kind of relegate it to the early days of dating, [but] so much of our intimacy can be generated from kissing, especially from more than a peck. So it's really relevant to adults. I think that taking the time to actually focus on kissing and integrate that into your sexual life or your intimate life is really crucial for connection between partners.

Do you hear from adults concerned about their kissing skills? How can one get past the worry that they're not a good kisser?

In the context of singledom, there's this idea that if you aren't a good kisser, then it's hard to get past that kissing stage. It's hard to move beyond that into something more. And that can be scary. If you don't know if you're a good kisser or don't have much experience, we aren't taught to communicate about these things to our partner. So we're not taught that this is something you should talk about — that you should just like, somehow magically know how to do it. And that in and of itself can create a barrier for wanting to learn or be open to talking to your partner about it, to see what their kissing style is, to see what they might like.

So I encourage people to really explore that together. Like, what do you like about kissing? Do you like a lot of tongue? Do you not? It can be great, I think, to make this into something fun or funny where you take turns and one of you leads the kiss and then the other one leads the kiss. And [then talk about] the differences in your styles of kissing, or even just talking about where you learned to kiss. That exercise and experimentation can be fun, no matter if you're early in a relationship or much later in a relationship.

Can couples who've been together a long time use kissing to get closer?

As relationship length increases, people tend to forget about sex. Sexual frequency decreases because a whole bunch of other things come in the picture and you just end up having to address those things first. So your sex life could be one of the first things to kind of fall off the priority list. One way to spark that intimacy again and one way to really feel that connection is to take the time each day to have a meaningful kiss. Not just a peck on the lips as you leave the house, but to take a moment and have a six-second kiss. John Gottman is a well-known researcher and therapist and he found that kissing can improve the health of your relationship if you allow for it to be six seconds. That six seconds has allowed it to be long enough that you're paying attention and you're feeling that connection.

It can feel kind of weird to go back and address kissing in the context of a long-term relationship, or when you're much older. But if you think about the early part of [your] relationship, it can be really fun to kind of think about how exciting kissing was, because those are the things that sparked that intensity for you both. For many people, [it] can be really, really powerful ... to revisit that, to revisit those early days and think about the power of the kiss.

Are there any foolproof techniques you suggest for people who are self-conscious about the way they kiss?

Technique is a funny thing, it can be so different. So talking to the person that you're kissing and even acknowledging or being vulnerable in the way of saying, "I don't know that I'm that great of a kisser; can you help me?" To show vulnerability can be a really positive thing in a relationship and can be something that you two can work through together. It also takes the awkwardness away from your partner, from them having to say something. It's sort of like you're beating them to the punch. It's allowing them to know, "Hey, I feel your body language. I know that you don't seem to really like my style of kissing. And because of that, I would love to know what you like."

So, a couple of foolproof things. The baseline is, start slow and soft — don't go right to tongue down [their] throat. That approach is really important. Having that buildup and having that ability to feel the heat building in a longer-term relationship, that's harder, too. But that buildup can be really powerful.

At what point should couples reach out for help if they're struggling with intimacy?

It's totally normal to feel [intimacy] fluctuating. We have this familiarity with our partner that really takes away from that spontaneous desire, right? And it's really only cause for concern if you're wanting to avoid any sort of contact with your partner, or it is causing relationship issues and you don't seem to be able to communicate about it.

Kristen Mark is a University of Minnesota sex and relationships researcher, educator and therapist. kristenmark.com