Dude, I have your solution.
Go out to a buffet, like one of those all you can eat joints. Chinese might be a bit overboard though. Anyways, here’s what you do. Clean the cat’s litterbox. Dude, shut up! Just do it! Ok, put fresh cat litter in it. What? You…aaargh! Go to the store and buy some. Jeez! Ok, now poop in the cat box. Make it big. Do the wiping and such at an actual toilet. Cats don’t like to use TP. Ok, make sure the cat doesn’t poop in the litter box. I don’t know, lock him in the closet or something, you never use that vacuum anyways. Next day go to the Vet and say “Sir Rasputin the Spock! made a huge doody! Are his poopy parts ok?” Make vague references to large things and small orifices throughout the examination. When she assures you that your cat’s anus is intact, express doubt. Tell her that even though the Vet says one thing, you trust her more than anyone (or some sort of other BS).
If she seems dismissive, wait for her in the parking lot with that 1960’s Batman style net, and toss her in your trunk. The rest is academic.
If she seems receptive, ask her what her favorite charity is so that you can make a donation in her name to it. When she replies say “Get out! That is also my favorite charity! Are you a super platinum member?” Since this means nothing at all, she will say no. Ask her to have a coffee sometime (if her nipples get hard, just ask if she wants to do it, it saves a step). At the coffee shop you have various options, “wanna see my hybrid car?” “I bet I can drink more Kahlua than you!” “I’ve never seen a women’s restroom, could you show me?” and the ever popular “Is that a real Monet? drop roofie into latte”. The best is to ask her if she wants a refill because you love hearing about her “desire to revive skunks that have been hit by cars” then you go to the barista (another term for coffee getter) and say that “My fiancee needs to have her medecine with hot liquid, could you blend this in?” Hand the dude two roofies. He might wink at you, because he does it himself.
Once you have her unconscious in your car, …uh…Duuude! You were gonna DO stuff to her! You sick freak! Leave her body at the local fairgrounds and head home, making sure to kill a pizza delivery guy on the way (wearing his skin of course). The next day, poison the mailman, and put a knife in his hand. Leave the pizza guy skin next to him, along with a ton of random coupons just to keep the cops guessing.
Man, you really messed this thing up! Where did you get such a stupid idea?