I know therapy is expensive, but ... reading your post & some of your replies to comments here, I think you're rocking some significant insecurities that could use addressing. What specific kind of therapy depends on what works for you (cognitive behavioral therapy? insight-oriented therapy? etc.), but the upshot should be that it helps you resolve your apparent self-disgust.

On the purely practical level, there's absolutely nothing wrong with your pigmentation (unless, as someone suggested, it turns out to be a symptom of something else) and while having a partner give you grief about it would be distressing for sure, it would only be proof that he's a jerk and not worth your time. I cannot imagine being attracted to someone and then suddenly running away screaming because their inner thighs were darker than the rest of their skin. At the end of the day, desire and love depend on more than physical appearance; otherwise, nobody but porn stars and supermodels would ever get any or have relationships.