Why have Michael's feeling about his home changed in the novel, You Are Here?

When Michael and Natasha were together, the house felt like home. "In her absence," Michael finds "it hard to be at home for any length of time" (13). When he is spending time alone in the "neat and pleasant two bedroom terrace house," Michael feels as if "something [has] gone missing, as if he'[s] been visited by neat and courteous burglars" (14).