It would be one thing if he just searched and found them, but he went through the trouble of creating a ruse to specifically gain access to their bedroom and also found pills in a location that most folks normally dont keep medicine at.<quoted text>
He probably searched everywhere he could until he found something. He opened every door and drawer that wasn't locked. That's pretty common behavior for people like that, so I'm not sure why you're finding that hard to understand.
The girl also didnt dump him on his face after that. A normal woman dumps a guy who is a pill popper, especially one who steals from her folks. A woman who is also a pill popper, doesnt.