Scott Schimmel wrote:
 

        Actually, there's a small problem with that... he didn't wish
for Belldandy as a fiancee, just to have a fiancee who was that
understanding.
        When Keiichi made the wish, Bell twisted it a little, due to
their past history, but there's no reason she should do the same for
Ranma... right?

Yes, as understanding as her.  How many people do you know that is
understanding as Belldandy.  


This happens right after the wish is said (Takes only a second in real
time)

<Belldandy mentally searching the database for the following criteria>
Ok...
Give me a count of all girls:
1. that are understanding as me
2. that is not married
3. that is currently not in love with anyone
4. that lives in Nerima
...
... [0 found]
Ok, change 4 to lives in Japan.
Give me a count of all girls:
1. that are understanding as me
2. that is not married
3. that is currently not in love with anyone
4. that lives in Japan
...
...
... [0 found]
Hmm, change 4 to lives in Asia.
Give me a count of all girls:
1. that are understanding as me
2. that is not married
3. that is currently not in love with anyone
4. that lives in Asia
...
...
...
... [0 found]
Oh dear, all right remove 4
Give me a count of all girls:
1. that are understanding as me
2. that is not married
3. that is currently not in love with anyone
...
...
...
...
... [0 found]
What! That can't be! Remove 3
Give me a count of all girls:
1. that are understanding as me
2. that is not married
...
...
...
...
...
... [2 found]
Only TWO!?
[sigh...] Please list the 2 people
...
...
...
...
... [Kasumi Tendo, Tendo Dojo]
... [Belldandy, Heaven] 
Oh my... That won't do, Kasumi's already in love with someone else.
[sigh...] I can't take Kasumi from her love...

<Belldandy ends search>

Wish granted...