、。
She's shy, which makes me like her even more.
Literal
She [topic-は] shy [because-なので], more-and-more she [subject-が] like is.
ますます ('more and more, increasingly') intensifies a comparative or progressive quality. なので chains the na-adjective 内気 with the soft reason ~ので. Note 彼女が好きだ — 好きだ takes が for the thing liked. The implicit subject of 好きだ is the speaker (first person).