Early on in a crush or new relationship, it can be difficult to distinguish between the normal excitement associated with attraction and the obsessive phenomenon, says Kat Van Kirk , PhD, a licensed marriage, family, and sex therapist and resident sex expert at Adam & Eve . However, she says that a good starting point is to ask yourself whether the infatuation is rooted in fantasy or reality — if it's the former, you may be experiencing limerence. So if you find yourself obsessing over a stranger or acquaintance's Instagram or Twitter feeds, that may be a good time to do a gut check. Of course, limerence can also be experienced with a crush you actually have a chance with (though, like Dr. Van Kirk said, it's normal to feel nervous or excited about a crush or someone you're just starting to date, to a point).