Complex sentence: Nearing the end of the book, she is surprised to learn of Dimitri's still strong feelings for her, feelings he had previously denied to protect her, and to Dimitri's strong disbelief, she returns his feelings and they reunite once more.
Split into simpler sentences: Nearing the end of the book, she is surprised to learn of Dimitri's strong feelings for her, feelings he had previously denied. To Dimitri's disbelief, she returns his feelings and they reunite once more.