The tragic story of Antony and Cleopatra is well known, and Shakespeare's version of the tale warns against overzealous love.  In the first scene of the play, Philo speaks to Demetrius about Antony's abandonment of his military duties,

"His captain's heart...reneges all temper."

Then, Antony and Cleopatra enter.  Antony is clearly obsessed with the Egyptian queen, though she seems to be more realistic about the relationship.  When a messenger enters with what Antony assumes is unwelcome news from his commanding officer, Caesar, Cleopatra urges him to hear it.  That's when Antony cries,

"Let Rome in Tiber melt, and the wide arch

Of the rang'd empire fall! Here is my space,

Kingdoms are clay; our dungy earth alike

Feeds beast as man.Tho nobelest of life is to do thus"

as he embraces Cleopatra.  He has clearly decided to abandon his former life and his position in the Roman army to be with Cleopatra.  In effect, he has decided, in this moment, that love of a woman is more important than love of one's country.