Your problem is inadequate blood flow leading to incomplete healing and partial thickness skin loss in the narrow flap behind your ear. This can be a result of natrually poor circulation (such as in diabetics), or in vasoconstricted circulation (such as in smokers, nicotine users, or those exposed to second-hand smoke).
Unfortunately, it can also occur in patients who have normal circulation and do not smoke or use nicotine--it's more rare, but can occur. I agree with my colleagues that this will heal remarkably better than it looks it could ever be right now. Careful follow-up and wound care is critical to minimize further tissue loss and maximize healing.
Just for those patients that might be wondering if this common: this is extremely unusual, but this patient's problem is partially a result of the incision design. The post-auricular (behind the ear) incision goes high behind the ear, but instead of crossing into the scalp at this high point, the surgeon chose to create a long, narrow skin flap by bringing the incision down along the hairline. (The discussion about the pros and cons of this choice are outside the scope of this answer, but relate to avoiding a "notch" in the hairline.)
Back to basic plastic surgery--a long narrow skin flap undergoes inevitable necrosis (skin death) at the tip of the flap because of inadequate blood flow to this area. Even in facial skin, where the circulation is unusually robust, the behind-the-ear skin is furthest from oxygenated arterial feeder vessels, and creating a too-narrow and too-long flap increases the risk that this can occur. Even if this incision design is chosen repeatedly without apparent problem, in certain patients, perhaps ones with just a tiny bit less blood flow, lower blood pressure, or an otherwise minor skin bacteria contamination, dead skin can occur, and the suture line breaks down, as it did in this patient.
Tummy tucks involve lifting large skin flaps as well, but ones that are hip-to-hip wide, so the blood flow to the "tip of the flap" is correspondingly greater. But, excessive tension, bleeding, superficial infection, smoking, diabetes, etc. can cause the same skin necrosis problems in the abdominal skin most distant from the blood supply (just above the pubic incision in the center) or where the blood supply is narrow and constricted (the umbilical stalk).
Neither operation is "difficult" for experienced and fully-trained ABPS-certified plastic surgeons, but both require attention to detail, proper adherence to basic plastic surgical principles, and careful incision placement. But this could happen to any of us, or any of our patients. BTW, it wasn't your fault that you gave a little tug. This would have happened anyway. Hang in there. Best wishes!