My wife rides her road bike with mountain bike shoes with SPD cleats. I have the tension set on the pedals almost as low as they'll go. Her feet come out with very little effort. Everyone riding clipless pedals will fall eventually, even your husband. It's inevitable.

I recommend learning to ride with clipless pedals in a low traffic neighborhood that's safe. Practice clipping in and out, exaggerating the motion to reinforce the movement. Clip out early, long before you need to come to a stop. Lastly, I recommend always clipping out with the same foot when coming to a stop, to develop a habit that occurs without thinking. There's debate as to left or right foot, I don't care, just one. Certainly you'll need to unclip with both, but as a matter of habit, stick to reinforcing one foot so that you're not hesitating when it comes to an uncertain situation.

Good luck!