There is no evidence to suggest that it is true that Sultan Mehmet II stabbed his wife. The story is a little reminiscent of the poem by Robert Browning, Porphyria’s Lover, in which the misguided narrator strangles his lover in order to preserve the moment of their love.
Porphyria worshiped me: surprise
Made my heart swell, and still it grew
While I debated what to do.
That moment she was mine, mine, fair,
Perfectly pure and good: I found
A thing to do, and all her hair
In one long yellow string I wound
Three times her little throat around,
And strangled her.
See the whole poem here.