Robert Griffin III is making it clear ... his marriage is dead -- claiming in divorce docs there is ZERO chance of a reconciliation.
The Cleveland Browns QB filed for divorce from his college sweetheart Rebecca Liddicoat earlier this month -- and in court docs obtained by Bossip, RG3 spells out why he pulled the plug.
"The marriage has become insupportable because of discord or conflict of personalities between petitioner and respondent that destroys the legitimate ends of the marriage relationship and prevents any reasonable expectation of reconciliation."
And if that wasn't clear enough, remember RG3 tatted his NEW girlfriend's name, Grete Sadeiko, on his arm to hammer the point home.
In the divorce docs, filed in Texas, RG3 also says he wants Liddicoat to have primary physical custody of their 1-year-old daughter ... and he has agreed to pay child support.
However, Griffin notes that he wants to be "joint managing conservators" -- which would give him shared authority to make major decisions in his daughter's life.
So far, Liddicoat has yet to comment on the divorce.