Dude, this is how you're supposed to fuck your wife in the ass... 1) she's willing to do it so take you time anyway and get her butt hole thoroughly lubed up. she was trying to give you a hint. Listen. 2) Slip in slowly , you wont' be able to slide in your whole length until you've gotten her sphincter muscle loosened up and that takes slow short thrusts. After she starts to gape the you can go for the heavy thrusting if that's what she wants.