I’m careful when reading those reviews on Goodreads. As far as the relatable comment. I notice that complaint quite often,along with likeable and it baffles me. Most of my favorite books are with main characters that I do not find relatable or likeable. Gone With the Wind. Both Scarlett and Rhett, wow, not likeable characters. The movie softens them. Anna Karenina, another character that I just cannot relate to at all but love that novel. I’m assuming time period has a lot to do with both of those novels. More current novels. Gone Girl, both main characters, yikes! Girl On A Train. Holy Cow, I wanted to shake that woman however I totally enjoyed the story. I’m reading The Summer Before the War and the main woman character, she is driving me insane (again maybe time period making it hard to relate).
I could ramble on and on. I agree with Jeremy, keep writing your interesting characters. Listen to your friend that warned you about reviews (although I would do the same, read and then dwell) and try to avoid them or at least come to terms with their sting.
Now I’m off to find out more about your book, Follow Me Into the Dark, sounds like your character, Kate, will just drive me insane while reading however those novels tend to stick with me long after reading and quite frankly those are my favorite novels.