Signs of mutual attraction vs. one-sided attraction?

Anonymous
A lot of people are closed books, so it's hard to tell if they like you. What are signs of mutual attraction vs. one-sided attraction.

Attraction is often contagious, but what are signs your attraction is the product of an unspoken vibe the other person is sending? And how often is it not contagious, but just a one-sided attraction?
Updates
+1 y
Most girls I've liked have eventually admitted they liked me back (so I obviously got some vibe). But this current one feels like I'm not having much effect, though I'm very attracted.
Signs of mutual attraction vs. one-sided attraction?
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