Breaking in would require effort ...
This. The guy prefers the direct, yet efficient approach. Causing damage to physical property is a no-go for him, unless he has to.
Seems like KyoAni is doing it again. They're making an otherwise mundane story look interesting by featuring a girl who can stare deep into your soul with her big, sparkling eyes. And who seems to have a traumatic past that she is subconsciously repressing.