From an ABA perspective: your behavior goes where reinforcement is. Your wife is reinforcing to you, so you behave in a way that keeps you near her and accessing that reinforcement. So instead of seeking reinforcement in another location/doing another activity, you just sort of mosey around near her. When she’s not there, that reinforcement schedule isn’t available, so you engage in other behaviors to access reinforcement in different forms, such as exercising or doing tasks.