How does Plutarch's view of Cleopatra and Antony differ from that of medieval Christian moralists? Does Shakespeare agree with Plutarch?

As for Shakespeare's Antony, I would have to say yes, he
is responsible for his fall.

At the beginning of the play,
he is ruler of one third of the fledgling Roman Empire.  He is "stationed" so to speak
in Egypt.  Although he is married, it is no secret that he is having an affair with
Cleopatra.

When his wife dies, it opens the door for the
couple but because of the political situation, he marries Octavius's sister, Octavia. 
This does not stop the affair.

Foolishly Antony listens to
the queen and instead of fighting the invading Roman forces on land where he has proved
to be an excellent field command, he meets them at sea which proves to be
disastrous.

Antony made some very bad decisions, but he
made them and he is responsible for the result.  In the end, he had no other choice but
to fall on his sword.