This is really a very interesting love story to analyse and think about. Key to understanding what Lawrence does in it, however, is to realise how he saw society as a repressive influence that often created a tension between our private passions and our public standing. One of the many reasons why Lawrence spends so much time focusing on the characters once they are seized by their sudden passion is that he wants to explore this conflict, especially from the angle of Ferguson.
For him, an educated, professional man, he fights against the way that love disempowers him from an intellectual standpoint. After his quasi-baptism experience along with Mabel in the pool where she tries to drown herself, however, he yields regretfully to love. Note how his reason seems to combat his feelings. On the one hand, when Mabel says to him "Do you love me, then?" we are told that "his soul seemed to melt." However, just a couple of paragraphs later, note his feelings:
He had never thought of loving her. He had never wanted to love her. When he rescued her and restored her, he was a doctor, and she was a patient. He had had no single personal thought of her. Nay, this introduction of the personal element was very distasteful to him, a violation of his professional honour. It was horrible to have her there embracing his knees. It was horrible. He revolted from it, violently. And yet--and yet--he had not the power to break away.
Note the massive conflict within him, that despite his stern attentions to not be swept away by love, is won by his new-found passion for Mabel. He in the end follows his heart, and we are left with their impending marriage and the idea that their future life together may not be so easy as they continue to have their various struggles over love.