When Harem Met Sally

My ex just started dating a female friend of his. When we were together, I always worried about the chemistry I felt they had, and it hurts that they got together right after our breakup. Does this mean he's always had feelings for her? Does it cheapen our entire relationship?

--Bummed

"I only have eyes for you" is sometimes actually true, like when two people in a relationship are being held hostage together in the trunk of a car. Beyond small-space kidnappings, the reality is typically more like: "I only have eyes for you. And you. And you. And, hey, is that your sister?" We're each attracted to a whole crop of people. However, attraction doesn't necessarily lead to action, at least for those of us who have a psychological moat holding us back. It's largely two things that keep us from sneaking out and having sex with the hot neighbor: love for the person we're with and a personality trait called conscientiousness. Conscientiousness, which has a bunch of letters in common with "conscience," is defined by social and personality psychologist Brent Roberts and his colleagues as "the propensity to follow socially prescribed norms for impulse control, to be goal directed, to plan, and to be able to delay gratification." A person with a solid helping of conscientiousness cares about the impact of their behavior on other people. However, being attracted to somebody happens automatically; it isn't a feeling we can decline like a questionable package. So, conscientiousness does not prevent a wandering eye, just wandering sex parts that get busy in its wake. Even people high in conscientiousness probably have a mental file drawer of potential partners -- "backup mates" -- even when they have a partner they love. Research on backup mates by evolutionary psychologists Joshua Duntley and David Buss suggests we evolved to have these in mind, at least subconsciously, to shorten the reproductively costly breaks between being dumped or having a partner die on us and landing their replacement. Ultimately, you have no control over another person's feelings. What you can control are your choices, using love (plus physical attraction) and conscientiousness as a guideline for whether to stay or move on. Regarding conscientiousness: A man whose actions day to day suggest he's ethical is a man who's less likely to end up in bed with somebody else while he's still in a relationship with you. As for love and attraction, a man who seems to have serious hots for you, sexually and as a person, is more likely to stick around and keep loving you. You'll still probably catch him glancing at sparkly ladies at parties, but try to keep in mind that window-shopping is not the same thing as robbing the store. (Breakfast at Tiffany's; lunch at Rikers!) ... For pages and pages of "science-help" from me, buy my latest book, "Unf*ckology: A Field Guide to Living with Guts and Confidence." It lays out the PROCESS of transforming to live w/confidence.