Editor's Note: (Ian Kerner is a licensed couples therapist, writer and contributor on the topic of sex for CNN. )
(CNN) It's called "micro-cheating": the small, seemingly innocuous acts of flirtation that don't necessary qualify as cheating but might be considered a little sketchy by your partner.
Many of us have experienced flirtatious relationships with friends and never acted on them sexually. Are these friendships signs of infidelity? Should you be worried if your significant other is attracted to someone else? Or could a little harmless flirtation actually be good for your relationship?
Flirtation is normal, sex therapist Tammy Nelson said. "Why shut down your natural feelings of attraction for someone just because you are in a monogamous relationship with someone else?" she asked. "You might be married, but you're not dead."
A flirty friendship could help feed the flames of your relationship, but it depends on the couple. "In some cases, flirting outside the relationship enhances the primary relationship, and in other cases, it siphons energy from the primary relationship," marriage and family therapist Nicolle Zapien explained. The key is to know your partner and to communicate about the friendship before it becomes a problem in your relationship.
Sometimes, flirtatious friendships are just fun and entertaining, and each person has a keen awareness that the relationship would never go further, sex therapist Holly Richmond said.
"People like to feel wanted, to feel desired, and having a flirtatious friend can elicit those emotions," she explained. "I encourage clients to ask themselves, 'Would I behave this way if my partner were here?' and 'How would I feel if I saw my partner behaving like this?' This takes self-awareness, honesty and empathy for your partner's position."
Having sexual fantasies about someone doesn't mean you can't be "just friends," Nelson said. In fact, most of us have sexual fantasies about people other than our partners. "But some flirting can lead a person on," she added. "Sending photos, being sexually explicit -- these are all things that you wouldn't want your partner to do, so why are you doing them?"
You can take steps to maintain a flirty friendship without crossing the line. "Keep conversations away from intimate or romantic topics. Don't comment on appearance or give excessive compliments. And keep an extra step of physical distance in face-to-face conversations," sex therapist Peter Kanaris advised.
If your partner still feels threatened by your interactions with another person, it's your job to remove the threat. "You have to ask yourself, 'What's more important: the thrill I'm getting from flirting or my core relationship?' " sex therapist Deborah Fox said. "If the answer is 'the thrill,' then you're putting your relationship at risk."
Keep in mind that the Internet is no less a threat to your relationship than in-person flirting. "In some ways, tech is more dangerous," Zapien said. "People say things that they would never say face to face, and online relationships have the ability to get very close or very sexual very fast without the benefit of facial cues."
It's completely fair to ask your partner to limit contact or change the nature of a flirty friendship, but you want to be careful about how you raise the topic. "If you're uncomfortable with a relationship your partner has with someone else, communicating about it is an important first step," sex therapist Rachel Needle said. "Spend time on your own trying to understand why you are uncomfortable with the relationship, as well."
Licensed mental health counselor Kristie Overstreet suggests making sure "that you aren't being impulsive or irrational in your request. If the relationship bothers you and is affecting your connection with your partner, ask for it to change. If your partner minimizes what you are feeling or requesting, then you need to have a conversation with them about your needs in the relationship."
One way to spark a discussion is by staying curious rather than accusatory. "You can try a script like, 'I'm curious about your relationship with your friend ____. It feels flirtatious to me, like you are or want to be more than just friends. Does it feel different than your other friendships to you?' " Richmond said. "Hopefully, this will keep your partner out of defensiveness and able to respond in a way that feels respectful and informative."
What's worrisome to some couples can seem inconsequential or even fun to others. Only you and your partner can determine -- together -- what's acceptable to you in terms of flirting. So keep the lines of communication open.