hollywood marriages aren't all about love.
they are mergers and deal with increasing star captial - if he marries woman ABC and she marries man XYZ, then they will get more attention over N amount of time, meaning their increased exposure leads to more roles that they are selected for, increasing their total revenue.
whether they love each other or not doens't matter - they can even cheat and that just helps it out even more - that gets them more press, and keeps them in the eye longer - more interviews on how they feel about it, etc etc.
the more people are about it, the more it keeps them at the top of the A list, which means they stay in the highest pay bracket and are in the "best" movies ("best" in the sense of what pays the most and will sell the most tickets).
to see it for anything else is a nice thought, but likely not the case.