MTO WORLD EXCLUSIVE: Floyd Mayweather Suffers His FIRST EVER DEFEAT . . . His FIANCE DUMPS Him . . . Despite Floyd Offering Her $250 MILLION To Stay!!!!

: Floyd Money Mayweather is possibly the GREATEST boxer of our time. He NEVER loses – not in the ring . . . and not in a BUSINESS MEETING. He amassed a PERFECT record in boxing . .. and a $500 MILLION fortune.

But exclusively learned that he may have lost the most important thing to him . .. his FIANCE Shantel Jackson.

As reported the pair split up EARLIER THIS YEAR, but THIS SUMMER the two reconciled. And for a tine, it looked like the two were finally going to be walking down the aisle.

Well that IS NOT HAPPENING. learned that Shantel BROKE UP with Floyd a few months ago. Her reasoning is that she does not want to be in a marriage, unless Floyd is 100% faithful. Heck, she would prolly settle for 90% faithful . . . but Floyd offered NONE OF THAT. According to our snitch, Floyd wants to be allowed MULTIPLE SIDE CHICKS.

But that’s not the CRAZY part of it all. EXCLUSIVELY learned that before Shantel left, Floyd offered to MARRY HER LEGALLY – with NO PRE-NUP, if she agreed to his “side chick” terms. Floyd has a fortune worth about $500M . . . and without a pre-nup, Shantel would be entitled to as much as HALF OF IT.

Despite Floyd’s VERY GENEROUS OFFER . . . Shantel still said no.

But the love story between Floyd and Shantel is NOT over. learned that Shantel still LOVES THE CHAMP, and is willing to get back with him . . . and even marry him, if he cuts off all the SIDE CHICKS.

Shantel was photo’d last night, ALONE, at the Basketball Wives premiere party. And she looked AMAZING!!!