This is the same rag that also ran all the Palin affair rumors and fake stories about Trig not being her baby, etc.
In all fairness, they've been right sometimes: Rush Limbaugh's drug problem, John Edwards's affairs, etc. That being said, the Enquirer has gone all-in for Trump this election cycle and, with that in mind, anything they report in this cycle should be taken with a heavy grain of salt.
Note that the story is about private investigators investigating rumors of it, not actual proof—just allegations. It's a flimsy case.