I only made it 16% of the way through this one (thank you, Kindle, for pointless specificity). My first issue was with regards to the hero reacting to his father's death, NOT with the vow to kill the murderer. Oh no. He was going to wait for said murderer to find a wife, settle down, have children, and then our fine boy was going to kill them all. That's pretty darn premeditated and creeptastic. Skip forward to the "present", humans are extinct, our heroine, despite seeming pretty normal all around, claims she's never experienced an emotion. She claims this just as she's, well, experiencing emotions for the first time. And growing boobs and new hair. Yup, insta-puberty. Raging hormones, new body... despite the deep psychological consequences of having your face changed (in the real world), she reacts to her "new self" pretty well. Especially considering the fact that physical attraction sends her off the deep end, but for some reason a complete identity/species change doesn't flip her switch.
Then we get to the goodstuff, the "Fated Mate" explanation. Both hero and heroine are fighting their attraction when Kelvin decides to explain some little "quirks" of Razorback Pookah biology. They can only have sex with a woman once (winners). If she's not their mate, they're never interested again (typical). If she *is* their mate, they'll never want anyone else again (awww, that's sweet), unless they sleep with her on any day other than the Solstice, in which case, even though she IS their mate, they'll never sleep with her again and live life alone (what the hell?). In addition to being silly arbitrary, this little science lesson sucks any anticipation that may have survived thus far right out of the book. Let me tell you a secret, they're going to sleep together on the Solstice. Not until then, nope, feel free to skip all the weird family feuds and heavy breathing, they're going to wait until the Solstice. Someone will probably try to kill them or they'll have decided they're mortal enemies or Izel will have to chose between Kelvin and her "family", but it's going to happen, they're going to bang. And I have no desire to jump through more weird narrative hoops and wait for them to just get there already.