Nikki Bella on Double Dating With John Cena, 'There's Boundaries'

Nikki Bella says she's "so happy" John Cena has found love again ... but don't expect the old couple to break bread together with their new partners anytime soon.

As we previously reported ... Cena was spotted makin' out with his new GF, Shay Shariatzadeh, on a steamy date in Tampa over the weekend.

TMZ Sports spoke with Bella -- who's now dating dancer Artem Chigvintsev -- about her ex's new romance .... and she's showing a lot of love for Cena.

"Oh my gosh, so happy for him," Bella says.

Of course -- Cena and Bella dated for years before breaking up in July 2018. John didn't give up on the relationship without a fight though ... he publicly pleaded to get Nikki back.

But, that's all old news and both sides have moved on ... and Nikki says she's down to be friends with Cena.

But, as for a double date with Artem, John and Shay??? Probably not gonna happen.