How to gauge if someone is in love with you:
People who feel a connection naturally mimic each other. People who felt strongly about a romantic relationship they were in did not mimic an attractive, opposite-sex third party nearly as much:
Based on the recent literature indicating that nonconscious behavioral mimicry is partly goal directed, three studies examined, and supported, the hypothesis that people who are involved in a romantic relationship nonconsciously mimic an attractive opposite-sex other to a lesser extent than people not involved in a relationship. Moreover, Studies 2 and 3 revealed that romantically involved persons tended to mimic an attractive alternative less to the extent that they were more close to their current partner. Finally, Study 3 provided preliminary support for a potential underlying mechanism, revealing that the effect of relationship status on level of mimicry displayed toward an opposite-sex other is mediated by perceived attractiveness of the opposite-sex other. The present findings suggest that behavioral mimicry serves an implicit self-regulatory function in relationship maintenance. Implications for both the literature on relationship maintenance and the literature on behavioral mimicry are discussed.
Source: “Mimicking Attractive Opposite-Sex Others: The Role of Romantic Relationship Status” from Personality and Social Psychology Bulletin