How we cite our quotes:
Mr. Rushworth was from the first struck with the beauty of Miss Bertram, and, being inclined to marry, soon fancied himself in love (4.10).
Mansfield Park explores the idea of falling in love as a deliberate choice versus falling in love involuntarily. Mr. Rushworth is predisposed, or wants to, fall in love and get married and therefore he falls in love quickly with the first person he meets.
Edmund was sorry to heart Miss Crawford, whom he was much disposed to admire, speak so freely of her uncle. It did not suit his sense of propriety, and he was silenced, till induced, by further smiles and liveliness, to put the matter by for the present (6.32).
Edmund's confusing relationship with Mary begins very early on in the book. Edmund and Mary have a fascinating relationship – they alternately attract and repel one another and neither can completely sort out whether or not they love or dislike the other. What's interesting, and realistic, is that they end up doing both – loving one another in spite of certain "flaws," and often disliking aspects one another in spite of their love.
[Julia] had loved, she did love still, and she had all the suffering which a warm temper and high spirit were likely to endure under the disappointment of a dear, though irrational, hope, with a strong sense of ill-usage (16.21).
Heartbreak is a major theme in this book and Julia is one of the many sufferers. Mansfield Park presents love as very confusing and chaotic, filled with good and bad aspects.