Analyze the kind of yandere she is. If more dere than than murder crazy a hug would suffice. But if murder crazy part is greater you need something crazy as well like an on the spot proposal, hopeful that will appease her and hopefully you actually like that kind of crazy. If the murder crazy part is too great, travel to another country, learn to speak another language and change your name to start a new life.
Or just be a complete misanthrope and encourage the murder of all your those around you.