When an Angel has a chance

Kristen craves for one thing. To be normal. She's the only angel known with black wings and she knows she's different. The day she was assigned to be a guardian angel for the firs time she was thrilled. Then she finds out it's to a young arrogant possessive Alpha who can't keep sleeping around. What happens when she finds out she's his mate when angels can't even have one? She knew she was different, but now she knows she's not who she thinks she is.