I disagree. Prof Bhaer was a father like figure who basically was inserted into the novel by Alcott to please her publishers and created a boring conventional marriage for Jo. There's very little passion there...and whatever existed is completely gone by Little Men and Jos Boys.
Jo and Laurie have that fire, and spark, and deep connection through their already established beautiful friendship...yes if they had gotten married, they would have argued and faught every once in awhile. But this is what marriages of equality are about (certainly not what she had with Bhaer), and their passion (not just in the romantic sense, but overall) would have kept them deeply in love and fulfilled with their relationship.
Instead we have Jo married to Bhaer - she gives up her independence, her writing, and becomes a conventional wife and a teacher. She basically gives up her dreams...and I found that very sad.