S. R. Faruqi:

The word aan has the meaning of 'coquetry', and also the meaning of 'moment'. If we look at it in one way, then the verse is a playful one, in which advantage has been taken of the idiomatic meaning of mar rahne or marne ('to become a lover of'). But from this very playfulness there arises a serious paradox as well: Because if in love of the beloved it's not difficult to pass out of one's life, then why doesn't he die? His dying hundreds of times proves that dying is not difficult-- but still he doesn't die. Thus either dying is very difficult, or else he doesn't in fact want to die, but rather wants to continuously enjoy the pleasure of dying hundreds of times over her every single coquetry.

If we take it in a mystical way, then there's a suggestion of the mood of dying in every single moment and rising up alive again, like 'those slain by the dagger of submission'. It's well known that at the time of the mystical-hearing [samaa((at] of the following [Persian] verse, Hazrat Qutb ul-din Bakhtyar Kaki gave his life into the care of the Lord:

kushtagaan-e ;xanjar-e tasliim raa
har zamaa;N az ;Gaib jaan-e diigar ast

'For those slain by the dagger of submission
At every moment, from the Unseen, there is another life.'

The true lover presents his life in the service of the beloved at every moment, and at every moment a new life is bestowed upon him.

FWP:

SETS == KYA
MOTIFS == LIFE/DEATH
NAMES
TERMS == PARADOX

The excellent multivalence of kyaa reinforces the paradox of which SRF speaks, for mushkil hai kyaa can of course be read in three ways:

=is it difficult?
=how difficult it is!
=as if it's difficult!

In the second line, the idiomatic 'to pass out of one's life' [jaan se gu;zarnaa] is a nice touch, because it evokes the Sufistic style of passing out of one's 'self' and thus becoming 'self-less' [be-;xvud]. It also has a flavor of volition, since gu;zarnaa is a verb used in the ordinary course of life (with it one can 'pass by', 'pass over', 'pass through', 'surpass', etc.). The English idiom 'to pass away' isn't as vivid, so as usual I stuck with extreme literalness.

The hyperbolic contrast of sau sau deaths for ek ek coquetry is enjoyable in itself. Alas, it's not possible to capture the effect in English.

Compare Ghalib's take on the same paradoxical life-in-death of the lover:

G{164,8}.