Forgotten Heir by Michelle Hercules

Have you ever heard of the curse of the middle child? It’s real, and it makes you invisible. Growing up in a house with three headstrong witches, I was usually stuck playing the mediator.
When I met Rikkon, I immediately felt a kinship to him. He wasn’t invisible like me, but in a sense, he was forgotten. We bonded over things we couldn’t control. He was struggling with his demons, and I was lost.
It was easy to fall in love, but that was when things got complicated. When I thought we could be more than friends, Rikkon’s past came to rip my hopes to shreds. He recovered his memories, and with it, the knowledge that he was never free to be mine. Someone else had staked a claim, a bond so strong, that no mortal human could break.
Foolishly, I made a vow to help Rikkon reunite with his true mate, not realizing that by doing so, I might have unleashed the wrath of Ellnesari in our world.