You forgot your toothbrush.
When someone you're seeing casually starts leaving things around your place to give you hints that they'll be back. Sometimes it can be a good thing. Sometimes not. Establish some boundaries if you have to.
The sex was great. Those kisses gave you butterflies in your stomach. How can this not be love? Right?
Better have that talk first!
Everyone wears a mask before the fights, before the sloppiness, before all the annoying character traits you hated in a person, Take things slow and get to know them first.
Seeing someone of interest get a long with everyone you know can be a great and wonderful thing. But just ask yourself if you are really ready to make things official and serious.