here's your last resort. Snap her neck and then push her down the stairs. If anyone asks, yes you were at her house from whenever till whenever (give the correct times you were there incase someone saw you coming or going). tell the police or whatever that you were "seeing" her but you two didn't have a solid relationship yet. When you left she was about to get into the shower/change the laundry/go to bed...ect. The police will assume she fell down the stairs breaking her neck. just don't be ruff with her or you'll leave fingerprint bruises.