I know that P&P and MP were published only a year apart, but they were originally written more than a decade apart, and it's interesting to see how JA's ideas on the necessity of marrying for love developed during that time (or at least, how she expressed them).

In P&P, it's pretty clear that JA was on the side of love, although in the novel, unlike in P&P2, Elizabeth never says that only the deepest love will persuade her into matrimony. Also, we have the sympathetic portrayal of Charlotte Lucas, which makes it clear that we're supposed to look at things from her POV, as well.

However, in MP, we have Fanny thinking "how wretched, and how unpardonable, how hopeless, and how wicked(!) it was to marry without affection" (ch.32). Then in ch.35, Edmund tells her "How could you imagine me an advocate for marriage without love?" and "You did not love him; nothing could have justified your accepting him.” Strong words! So marriage without love is now morally wrong as well as impractical, etc.

I wonder if JA's feelings, which always tended this way, simply clarified and strengthened over the years, or whether she simply felt braver in saying what she really felt by the time she wrote MP?