What impact does the oxymoron "violent delights have violent ends" in Shakespeare's Romeo and Juliet?

In Romeo and Juliet, Friar Lawrence's warning to Romeo that "violent delights have violent ends" introduces the paradoxical themes of love and violence.

Friar Lawrence's warning to Romeo that impulsive behavior and violent love can end badly goes unheeded as the priest urges the young man to "love moderately" so that love will last. Romeo ignores the conventions of his time in which a man would request permission from the father before marrying his daughter. Instead, Romeo exhorts the friar to secretly perform marriage rites for him and Juliet. When the friar realizes that Romeo and Juliet will act on their love with or without his help, he agrees to marry them.

Juliet ignores convention and acts impulsively as well. In fact, she even ignores the rules of convention that she has followed earlier, having promised her mother that she would consider Paris as suitor:

I'll look to like, if looking liking move
But no more deep will I endart mine eye
Than you consent gives strength to make it fly (1.3.99-101) 

Now as she awaits the Nurse to return from her meeting with Romeo, Juliet is impatient and hasty in her actions:

Now is the sun upon the highmost hill

Of this day’s journey, and from nine till twelve

Is three long hours, yet she is not come.

Had she affections and warm youthful blood,

She would be as swift in motion as a ball. (2.5.9-13)

The impulsive behavior of Romeo and Juliet continues throughout the play. For instance, Romeo threatens to kill himself while he is hiding in the friar's cell after having been banished from Verona for killing Tybalt in a moment of passion. He later rushes to the apothecary in order to purchase poison after having learned of Juliet's supposed death from Balthasar, and he then he hurries to Juliet's tomb.

Juliet, too, reacts to events impulsively. After having been ordered by her father to marry Paris, Juliet threatens to kill herself when she talks with the friar at the beginning of Act IV. The friar deters her from suicide, and she agrees to follow his plan to feign her death. Unfortunately, word of the friar's scheme never makes it to Romeo. Consequently, he purchases poison in order to kill himself so he can join Juliet in death.

Certainly, the extreme love of Romeo and Juliet leads to a violent end. From their great passion comes death, thus connecting the themes of love and violence.