5 Ways Men Secretly Cheat

Unless you’re a swinger, having sex with someone else counts as cheating. Oral, too. But then there’s the fuzzy area between friendship and infidelity—and chances are, your girlfriend sees those shades of gray as more black and white than you do.

“Men aren’t as attuned to identifying ambiguous behaviors as cheating as women are,” says Daniel Kruger, Ph.D., a University of Michigan psychologist, who’s studied gender differences in definitions of infidelity.

In other words, what you consider totally innocent could be her dealbreaker. Here are five signs you might be in an affair without even knowing it.

Related: 6 Signs She’s Thinking of Cheating