Here's the skinny ... an alleged "Comprehensive Media Plan" from the NFL star's reps at Full Scope Public Relations made the rounds online Tuesday night, seemingly suggesting Travis and Taylor's "Love Story" was all fabricated for press -- and that there was even a plan to break up on September 28.

It didn't take long for the one-sheet to go viral online ... especially since so many Swifties believe the pop star has finally found "The One" with the Kansas City Chiefs tight end.

Now, a spokesman from Full Scope categorically denies the alleged plan ... telling TMZ the document is "entirely false and fabricated and [was] not created, issued or authorized by this agency."

The spokesman added ... "We have engaged our legal team to initiate proceedings against the individuals or entities responsible for the unlawful and injurious forgery of documents."

So, Swifties can breathe a sigh of relief ... there's no "Cruel Summer" twist ending in Swelce's future.

Travis and Taylor have been dating for a little over a year, first linking up last summer after the football player tried -- and failed -- to give the singer a friendship bracelet with his phone number on it at her "Eras" tour stop in Kansas City.

The romance appeared to grow at warp speed, with Taylor attending several of Travis' home games ... later cheering him on at Super Bowl LVIII in Nevada. Travis also showed up to support Taylor, attending over a dozen of her concerts across the globe.

Fans of the couple were likely skeptical of the rumored breakup plan, too ... since Travis and Taylor were recently spotted all over each other enjoying downtime at the singer's Rhode Island home.