Bluebirds of irritation

We have a carefully constructed and positioned bluebird house in our backyard.  We must have the same pair we had last year now. The male overdoes his job of protecting but does get the idea that the other male he sees reflected in our windows is HIMSELF.  So, he keeps flying at the intruder, crashing into our windows.  I have talked to him, sent him texts and emails to no avail.  My wife has explained to me how bluebirds are lovely and have trouble surviving so she does not want me to go too far trying to discourage his crusade against strange opponents.