How we cite our quotes:
"She'll see those handsome eyes that she talks about, and then it will be all up with her. She's got such a soft heart, it will melt like butter in the sun if anyone looks sentimentally at her. She read the short reports he sent more than she did your letters, and pinched me when I spoke of it, and likes brown eyes, and doesn't think John an ugly name, and she'll go and fall in love, and there's an end of peace and fun, and cozy times together. I see it all! They'll go lovering around the house, and we shall have to dodge. Meg will be absorbed and no good to me any more. Brooke will scratch up a fortune somehow, carry her off, and make a hole in the family, and I shall break my heart, and everything will be abominably uncomfortable. Oh, dear me! Why weren't we all boys, then there wouldn't be any bother." (20.31)
For Jo, falling in love is dangerous because it will split her sisters apart. As each of them finds a love interest, she will be drawn away from the March family and into a new partnership that creates a different home.
"Mercy on me, Beth loves Laurie!" she said, sitting down in her own room, pale with the shock of the discovery which she believed she had just made. "I never dreamed of such a thing. What will Mother say? I wonder if her . . ." there Jo stopped and turned scarlet with a sudden thought. "If he shouldn't love back again, how dreadful it would be. He must. I'll make him!" and she shook her head threateningly at the picture of the mischievous-looking boy laughing at her from the wall. "Oh dear, we are growing up with a vengeance. Here's Meg married and a mamma, Amy flourishing away at Paris, and Beth in love. I'm the only one that has sense enough to keep out of mischief." (32.20)
Although Jo doesn't love Laurie, she seems to consider it her prerogative to match him up with her sisters. When her initial plan of marrying Meg to Laurie falls through, she develops a new plot involving Beth, and even convinces herself that Beth is already in love. Clearly, Jo hasn't really fallen in love with anyone herself yet, or she wouldn't think of it as a mechanical, controllable thing.
I think everything was said and settled then, for as they stood together quite silent for a moment, with the dark head bent down protectingly over the light one, Amy felt that no one could comfort and sustain her so well as Laurie, and Laurie decided that Amy was the only woman in the world who could fill Jo's place and make him happy. He did not tell her so, but she was not disappointed, for both felt the truth, were satisfied, and gladly left the rest to silence. (41.28)
Alcott has to employ every rhetorical trick in the book to convince us that Laurie and Amy really are in love. It just seems a bit creepy to have someone love one sister for two-thirds of the novel and then make a quick change and transfer his affections to another sister! Whether or not we believe in this new romance will depend on how convincing the narrator can be.