Princeweaver by Elian J Morgan

Their marriage is to save a warring kingdom. But in the process, it might destroy them both.
Born with forbidden, nature-infused magic in an occupied land, anxious apothecary Meilyr survives by keeping his head down. Until he ends up engaged to invading prince Osian in order to save his brother's life. Now, he is in a deadly game of cat-and-mouse to hide his true self.

When nobles in Osian's court are gruesomely murdered by the same magic that flows through his veins, Meilyr realises someone is seeking revenge for his homeland. As suspicion towards him grows, he and the prince work together to uncover the killer or risk losing the crown - or their lives.

Between court politics, unwieldy magic and a murderer on the loose, Meilyr must keep his wits about him. Especially as his feelings for Osian grow deeper with every passing day...
 
Princeweaver combines the court intrigue and slow-burn yearning of A Taste of Gold and Iron with the folkloric grounding and lore that readers of Naomi Novik and Stephanie Garber will enjoy.