The correct answer is there was no reason.
There was actually a reason but it was never stated publicly and it was because of all the affairs that occurred between them. They went to France to live outside of it all and not deal with repercussions and save their marriage.
The Wilmot Proviso prevented new states from becoming slave states, the compromise enabled them to become slave states if popular sovereignty wanted them to be. California was allowed to become a new, non-slave state, and in return Slavery was enabled and allowed in the south, strengthening fugitive laws even more. To everyone it seemed like a victory for a while.
There is no article so I can’t answer your question.