Why won't Catherine of Aragon just shut up?

Season 2 of The Tudors just started on Showtime. Catherine of Aragon was Henry VIII's first wife and Queen of England, but as she could not bear Henry any male heirs, he tired of her and eventually married Anne Boleyn.

Practically every scene with Catherine is her standing her ground, saying she's in love with Henry and that she won't leave him and that regardless of what happens she is Henry's lawfully-wedded wife and England's only rightful Queen Consort (which she avowed until her death).

Why can't she get it through her thick head that Henry doesn't love her and doesn't want her around anymore? And why would she want to stick around in a loveless marriage? Pathetic idiot. I would've cut her head off just to get her to shut up.