The love of Romeo and Juliet is a violent love; as such, it affects death.
In Act II, Romeo comes to Friar Laurence and pleas with the priest to perform the marriage ceremony for Juliet and him; afterwards, the friar tells Romeo he hopes that Heaven will smile upon this marriage and sorrow not come to such a dangerous match. But Romeo recklessly replies,
...love-devouring death do what he dare.
It is enough I may but call her name. (2.6.7-8)
To this remark, Friar Laurence cautions,
These violent delights have violent ends
And in their triumph die, like fire and powder,
Which, as they kiss, consume. (2.6.9-11)
As the tragedy of Romeo and Juliet continues, these words prove prophetic. For, the foreshadowing of the violence connected to love in the first act certainly develops as Mercutio becomes involved in an altercation with the choleric Tybalt who challenges him because he is a friend to Romeo; then Romeo enters the scene and tries to ameliorate things, but his intervention ironically causes more conflict as Tybalt reaches Mercutio and slays him when Romeo gets in the way of Mercutio. Incensed that Mercutio, whom he loves as a friend, has been killed, Romeo then slays Tybalt, whom his wife loves since he is her cousin.
These acts of violence result in Romeo's being banished and Juliet's feigning her death to avoid marrying Paris, actions which then lead indirectly to their suicides as Romeo is not informed that Juliet is actually alive because Friar Laurence's man cannot enter Mantua. Further, Juliet's failed rescue from the tomb because Friar Laurence runs away causes her to discover Romeo's dead body. Indeed, the violent delights, violent passions of Romeo and Juliet lead to violent ends as Romeo kills Tybalt and Paris and then himself, and Juliet feigns her death only to kill herself in despair.