Sal actually has a specific love for him, not caring about him somehow in principle, which is the way of course that Dean cares.

not caring about him somehow in principle，现在分词短语作伴随状语或方式状语，“对他有真爱”，但在表现方式上却是“满不在乎的样子”（女孩子的特点）。

somehow 修饰 not caring，意思是说：不知何故（或莫名其妙地）不在乎。

of course 修饰 is，“当然是” 。它在定语从句 that Dean cares 之前，不属于 that 定语从句的，如果说 that Dean cares of course，那就是修饰定语从句 cares。