Virtuous is “good” with a halo. If you call someone virtuous, you are saying that person is living according to high moral standards. Someone virtuous is who you want leading your Girl Scout troop.
When you use virtuous to describe an action, like, "Your decision to cancel your vacation plans when your mom got sick was virtuous," it’s almost as though you’re referring to an ideal of goodness. In past centuries, virtuous was synonymous with virginal. In many 18th century English novels, for example, a woman didn't even have to be all that nice to be called virtuous; it just mattered that she was sexually innocent.