You know you love your yorkie when you cannot wait to get home to see him because he just puts that smile on your face after a long day/night of work.
You know you love your yorkie when you take the garbage out (ie: his dirty poop/pee pads) and take your yorkie along..just so he can have a 'mini adventure' and see the outdoors with you.
You know you love your yorkie when he can even get your boyfriend to say say (in a high pitched voice), "Aww..I love the little guy..he's so cute..I looove him" ...and then your yorkie bites your boyfriend's toe, and your boyfriend screams, and then... you and your boyfriend laugh together and just keep playing with your yorkie anyway.

(funniest moment ever in the 3 weeks i've had Luigi)
That's how I personally know I love my yorkie