In Mary Shelley's Frankenstein, why does the creature kill Henry Clerval?

has
foolishly made a promise to create a companion for the monster. However, he soon gets cold feet
over the idea. He's already starting to realize the full moral implications of creating the
original monster; the last thing he wants to do now is create another one. A further
consideration is that, if the monster has a mate, then together they'll be able to create a new
race on their own without any involvement on Frankenstein's part. Not only does that present a
future for the planet too horrible to contemplate, it also undermines 's original plan to have a
race of creatures who'd worship him like a god, owing their existence to him and him
alone.

So Frankenstein reneges on his promise to the monster. Not
surprisingly,is furious and seeks revenge. The monster still wants a mate, and he knows that
Frankenstein is the only man capable of doing so. It wouldn't, therefore, make much sense to
kill him. So he's not going to attack Victor directly, at least, not yet; he's going to get at
him through the people he cares about. That's why he threatens to turn up on Victor's wedding
night if his demands aren't met. And it also explains why he kills . He's punishing Frankenstein
for going back on his promise to create a companion. In doing so, he's adding to the crushing
burden of guilt which is already weighing heavily on Frankenstein's
shoulders.