Torgar the Molten by Cara Wylde

When the orcs invaded the human dimension, no one could stop them. War raged for years, and now the monstrous beasts have agreed to peace on two conditions: one, the human scientists must rebuild the machine that brought them into this world; and two, they must be provided with fertile brides to bear them orc babies.
Wendy Bennet is stuck. Stuck in life, stuck in her career, and definitely in love, where nothing worth mentioning has happened in years. She’s obsessed with her job as an investigative journalist, but she’s hit a ceiling, and if she doesn’t do something soon, those prizes she’s always dreamed of will never land on her shelf. She’s been interviewing orc tributes for a piece she’s been working on for months, but the problem is that once they are chosen by an orc and join a horde, they stop talking to her. Then she gets an idea – if she offers herself as tribute, she can get a story that will launch her to the next level.
Torgar the Molten has never felt lonelier. After he was gravely injured in battle and his mage brought him back to life, everyone has feared him and avoided him. No female wanted to mate with him, and now that he’s in the world of humans, he’s lost all hope of finding someone who will look past his monstrous body and see his soul. But if he goes to one of those institutes for orc tributes and takes a human bride, she won’t be able to reject him. Because the sole purpose of the system is to keep the peace between humans and orcs. When he sees curvy, sassy Wendy, he decides – he will make her love him.