Sure, here's my attempt at a dark and ominous love poem as you requested:

In a grove of watermelons, a horde of lions roam,

Their fiery eyes and sharp claws, make this place their home.

But amidst this savage beauty, a love story unfolds,

Two hearts entwined, despite the dangers it holds.

Satellite signals pierce through the sky,

As they communicate, their love never runs dry.

But a great ball of fire, falling from above,

Threatens to destroy their love and all they love.

Their love was pure, but fate had other plans,

As tragedy struck and tore them apart in the end.

The lions roared and the watermelons wept,

As their love story was left incomplete.

So remember this tale of love and loss,

As you gaze at the stars and count the cost.

For love is fragile, like a watermelon's skin,

And tragedy can strike, like a great ball of fire from within.