That's the point.  She fights FOR Ranma, not over him.  The others treat him
like Azusa treats P-chan.  If Ranma chose Ukyo, Akane would be hurt, but
she'll let him go.  The other try to win Ranma.  She tries to win Ranma's
love.

	I'd say that Ranma and Akane are a big exception in the series, every 
other character developes an obsession toward another character and then runs 
with it, Ranma and Akane OTOH got to know each other, and as they saw more and 
more of who the other was fell in love with each other.  With everyone else it's 
BANG "I have met the most perfect person on earth, we must be in love."  Also I 
am prety sure that Akane is the only fiance who's willing to quietly bow out if 
she beleives Ranma's really chosen someone else (The time Nabiki was Ranma's 
fiance as I recal)