The ending of the novel is considered happy, not merely because of the fortuitous marriages, but because our main character has grown into a better understanding of herself and those around her. Elizabeth shows strength and courage throughout the novel, but her final stand off with Lady Catherine is a great scene. She stands up for herself not even knowing that she still could get Darcy for herself. She admits to herself that she loves Darcy, and for a short while thinks that she will have to live with the fact that her past actions and false assumptions have put her apart from him. Darcy saves the Bennet family reputation in regards to the Wickham and Lydia situation not knowing how Elizabeth feels for him.
When Darcy comes back for the second proposal there is such a sense of joy because Elizabeth and Darcy are both in the same place now and are ready to be with each other, both having learned some truths about themselves first.
Darcy's initial pride and Elizabeth initial prejudice have resolved into the the true emotion they have now, which creates a very happy ending.
The ending of the novel is one that I would consider a happy ending. Elizabeth and Darcy finally manage to share their true feelings for one another. Through this they are now able to have a life together which they both desire. Mr Darcy turns out to be a much better man than Elizabeth could have ever expected.
Mr. and Mrs. Whickham do not have a happy ending, but not all relationships do end happy in real life. Should every situation have turned out perfect the book would have been too sappy and urealistic.
While Jane does not get the man who broke her heart, she gains a more sensible and caring man as a husband. I the end she has a better life ahead of her.