How does Austen present love throughout the book?

Austen presents love as something which is vital to a good marriage.  We see that the Bennets' marriage is a loveless one: Mrs. Bennet is a ridiculous gossip who is well-known for being socially inappropriate; Mr. Bennet can hardly stand her and retreats to his study to escape her whenever he can.  He admits that it wasn't love that brought them together, and look at where they've ended up.  Likewise, the marriage between Lydia and Mr. Wickham isn't founded on love.  Near the end of the novel, the narrator mentions that it doesn't take long for them to completely tire of one another. 
The relationships between Jane and Mr. Bingley, and Elizabeth and Mr. Darcy, however, are founded on love and both take some time to come to fruition.  In this way, Austen also presents love as something that takes time to develop.  The best, most egalitarian relationships in the book, then, are founded on love, and because love is something that takes time to grow, these loving relationships also require time.