The most insidious type of cheating isn't physical - here are 8 signs it could be happening to you

Sheri Meyers calls it an "affair of the heart," or "emotional sex."

You're hardly renting a hotel room together - at least not yet - but you're going out to lunch every weekday and trading intimacies, and when you get home at night, you can't stop thinking about them. Or, maybe you haven't met in person, but you chat online for hours at a time.

Emotional affairs are hard to define exactly. But as Kristin Salaky at INSIDER reports, they're becoming increasingly common - more so even than physical affairs.

Business Insider spoke to Meyers, who is a licensed marriage and family therapist and the author of "Chatting or Cheating," and Michele Weiner-Davis, who is also a licensed marriage and family therapist and the author of "Healing From Infidelity," about some key signs that you could be guilty of emotional infidelity.

Interestingly, Weiner-Davis said that many people in this situation insist they weren't looking to cheat - it just happened. But in reality, the road to infidelity is a "slippery slope," she said. "Every daily decision is bringing them closer and closer to moving from emotional infidelity to perhaps even a physical affair."