The former Heretaunga Intermediate School pupil from Hastings has lived in Ireland for 14 years but intends to return home in a couple of years.
The Kukri sports apparel employee and her fiance, Simon Broughton, of Taupo and a former Taradale rugby club player, are living in Dublin with their Irish-born son, Serge, 6.
"You just can't take the Kiwi out of the girl."
Before the kick-off, Serge had reiterated to his mother that he was an ABs supporter but he would back her in yesterday's test.
"Serge's into his rugby and all but yesterday he turned up at the grounds in an Ireland jersey," she said of her son who presented her the 50th cap on the field before kick-off.
It was daunting for Rosser to run out with the ball from the tunnel.
"I kept looking back and asking the girls to keep up behind me because I just didn't want to be out there alone."
Asked if she would play for New Zealand, she replied: "Definitely not. I'll never give up the green jersey for any country."
Her loyalty to Ireland is best reflected in Serge's "22 aunties" babysitting him to enable her time to train and play rugby.