Dak Prescott and Sarah Jane Ramos aren't going to be romantic teammates for life ... but, when it comes to their kids, they're driving down the proverbial gridiron in the same direction -- reuniting for their daughter Aurora's first birthday.

SJR shared photos from the special day ... including one with Dak, Aurora and older daughter Margaret -- all sporting big grins.

Ramos wrote on the pic, "How is this perfect baby 1 today? Grateful for the best day celebrating her."

While the other photos she shared mostly featured just her and the kids, one other pic also had Dak in it -- a photo taken right after Aurora was born.

As you know ... Dak and Sarah decided not to get married back in March -- with sources telling us it had been rocky for months and came to a head at their joint bachelor and bachelorette parties.

Sarah ended the relationship ... and later shared family photos that didn't include the Dallas Cowboys QB.

We learned they're handling custody amicably -- and the proof is clearly in the pics -- though recent rumors about Dak dating one of Sarah's almost bridesmaids, which she has denied, had many wondering how they'd get along.