S. R. Faruqi:

In the verse there's an interesting iihaam . The beloved was settled in the heart for some time; that is, she had made a home in the heart. Now the heart is desolate; that is, the beloved has emerged from the heart. This can mean that now in the heart love for the beloved hasn't remained, or else that the beloved, having made a home in the heart, destroyed the heart. Then the heart was destroyed, then the beloved didn't remain in it either. (The beloved left me, or else the fervor of passion no longer remained in my heart.) From jis and us the suspicion can arise that someone else's heart is being described. There's also an allusion to the toughness [sa;xt-jaanii] of the heart, because the heart remained inhabited 'for some time', and now it has gone to ruin. See {66,7}.

FWP:

I don't see exactly what SRF means the iihaam to be; perhaps he's using the term loosely.

Note for grammar fans: How coolly Mir simply omits the ne in the second line! Don't even think about it. It's not something anybody now could even dream of getting away with. And it's impossible to argue that it's really a truncated participle, because then it would be dekhe . He could be doing the same thing in the first line too, but it's impossible to tell, because the ne would be colloquially omitted along with the subject in any case.