How we cite our quotes:
[Jacob:] I knew it wasn't my imagination that my need for her was stronger than ever. Why was that? Because she was dying? Or knowing that even if she didn't, still – best-case scenario – she'd be changing into something else that I wouldn't know or understand? (15.125)
Jacob seems to be more afraid of Bella changing than of Bella dying, because unlike dying, her transformation into a vampire is something he can't relate to.
[Edward to Jacob:] "No. Not human. But she hopes to see Charlie again, anyway." (15.173)
Bella believes that there's a way for her to still have a relationship with Charlie after she turns into a vampire. Is that an understandable wish or is she being selfish here?
[Leah to Jacob:] "I'm talking about being a genetic dead end, Jacob." (16.107)
Leah's transformation into a werewolf have changed her human body and has possibly thwarted her ability to bear children.