Two UFC fighters are teaming up -- FOR LIFE -- because Thiago Santos proposed to Yana Kunitskaya ... and she said, 'Da!'
(Sidenote: She's Russian).
Thiago -- aka "The Sledgehammer" -- popped the question to his longtime GF earlier this week, using a ring he got from celeb jeweler Boodaddy Diamonds.
We're told the ring is 18k rose gold with a diamond halo. The center stone if a 2 carat round pink sapphire.
The two have reportedly been dating for a few years -- but Thiago decided it was time to level up -- so he took Beyonce's advice and put a ring on it!