Because I have trained him well.
Here is my patented list of ways to TRAIN your significant other.
1) Reward them for every little thing! Opened the door for you? Give him a kiss! Cooked you dinner? Give her a kiss! Cleaned up the house while you were gone? Give 'em a kiss! It's very important to let them know that you appreciate everything they do. This will make your significant other more likely to do things for you! Eventually you can phase out the rewards.
2) Disguise your requests for slave labor. Don't ask him to come
3) Never hesitate to correct your significant other when they step out of line. A swift, and prompt punishment is important whenever your significant other steps out of line, or they will continue their negative behavior.
4) Remember that rewards should be interspersed randomly after the association between a behavior and the reward is established. This way, they will continue to do the positive behavior hoping for the reward to come, because they never know when they will get it.
5) When out and about, if your significant other doesn't want to go along with you to a particular store, give him a sharp tug in the right direction. He will follow you happily.
Remember, folks, training your significant other is a lot like training a dog! Except better, because they don't pee on the carpet, and the best rewards get enjoyed by both of you! (i.e. sex)