All Lyin' Ted had to do was to explicitly declare that the article is false, that he has never cheated on his wife, and that his lawyers will immediately seek legal recourse.
He did not.
Where there's smoke, there's quite a fire..
BTW I just took a look at Trump’s FB page. All reference to Ted Cruz is gone completely. The only thing posted is optimistic posts about the campaign. If I was Teddy I would be concerned.