Simple sentences:
* The unloyal soldier betrayed his comrades.
* Her unloyal actions shattered their friendship.
* The dog's unloyal behavior surprised everyone.
More complex sentences:
* Despite their promises, the company's unloyal actions towards its employees led to a strike.
* Feeling betrayed by her unloyal friend, she decided to end the relationship.
* The politician's unloyal words, spoken during a private meeting, were leaked to the press, damaging his reputation.
Figurative usage:
* The weather was unloyal, changing from sunny to stormy in an instant.
* His unloyal heart never truly belonged to anyone.
Remember that "unloyal" often implies a betrayal of trust or a violation of loyalty. The word has a strong negative connotation.