Some may consider that the other love interests are but evanescent flings and/or lovers while Mashu's here to stay...
...Unless certain ones use the Grail to get an existing & physical body to live w/ you in your lifetime.
To which we have several. Which may be more than enough for everyone that wants them.
And we technically did get a boat load of money to live off for the rest of our lives w/ rooms to spare when we fix all the world ending stuff.
...I was trying to make a point about something but I forgot.