Vibrating roboginas could have hundreds of small artificial muscles looped around inside them, allowing them to rhythmically massage you and lock you balls deep inside them when you're about to cum.
They could also have high-resolution pressure sensitivity in three dimensions to know exactly what makes your peepee feel good.
The desires and emotions of robowaifus will eventually be fully programmable and editable. You'll be able to make your robowaifu crazy for you at the drop of a command or make her teasing or shy, whatever you want. She'll watch and analyze everything you do and learn how to moan and writhe perfectly in ways that completely break your mind.
A cheap solution you could rig up in the meantime is some simple haptic sensitivity and a mic recording your breathing. Train a neural network to detect your moans off the focking data and have her play moans or generated moans. The hottest part of sex is being in sync, breathing together, moaning together, cumming together, bonded together like one being, man and machine. Once she starts moaning from things that make you feel good it'll drive you insane.