1. Romeo seduces a 12-year-old girl when his first love, Rosaline won't put out.
2. He starts the quarell that leads to the death of Tybalt and Mercutio (though arguably he is not as responsible.
3. He impetuously decides to kill himself rather than honor the memory of his dead wife. This leads the impressionable Juliet to also commit suicide
4. He murders Paris. This is the most important part of Shakespeare's portrayal of Romeo. And this is also the scene that they leave out of most movie versions of the play, because you cannot see this scene and NOT think Romeo is a bad guy. Here it is in text:
Thou detestable maw, thou womb of death,
Gorged with the dearest morsel of the earth,
Thus I enforce thy rotten jaws to open,
And, in despite, I'll cram thee with more food!
Opens the tomb
This is that banish'd haughty Montague,
That murder'd my love's cousin, with which grief,
It is supposed, the fair creature died;
And here is come to do some villanous shame
To the dead bodies: I will apprehend him.
Stop thy unhallow'd toil, vile Montague!
Can vengeance be pursued further than death?
Condemned villain, I do apprehend thee:
Obey, and go with me; for thou must die.
I must indeed; and therefore came I hither.
Good gentle youth, tempt not a desperate man;
Fly hence, and leave me: think upon these gone;
Let them affright thee. I beseech thee, youth,
Put not another sin upon my head,
By urging me to fury: O, be gone!
By heaven, I love thee better than myself;
For I come hither arm'd against myself:
Stay not, be gone; live, and hereafter say,
A madman's mercy bade thee run away.
I do defy thy conjurations,
And apprehend thee for a felon here.
Wilt thou provoke me? then have at thee, boy!
O Lord, they fight! I will go call the watch.
O, I am slain!
If thou be merciful,
Open the tomb, lay me with Juliet.
Paris thinks Romeo is going to desecrate Juliet's grave. Romeo admits that he is going in there only to kill himself. So if Romeo had only listened and given in to the heroic Paris, he and Juliet would have lived (as well as Paris).
Anyway, the reason I am bring this up is that I came upon an article about Romeo and Juliet that was more in line with my interpretation of the play. I have great respect for Dr. Joseph Pierce and his Shakespeare scholarship. Check it out if you have the time.
And then there is another article that comments on the one above.