Here is the full list of all 11 Romeo Must Live achievements.
Started the game
Killed by one of Count Silvio’s Guards
Gave up on Juliet and married Concetta instead
Romeo gets defenestrated
Decapitated by Reiner
General Negroni marries Queen Brunhilda
Got shot by Reiner von Innstadt during a duel
Shot first and survived the duel
Died in a duel against Negroni
Married Juliet and lived happily ever after
Get Rejected by Juliet and become a tavern tycoon instead