Ex-international Darren Cave has said his generation "couldn't stomach" it if Brexit disrupted the "unique balance that makes Irish rugby so successful".
In a candid column for the Sports Chronicle, the Ulster centre said the Brexit deadlock was a "threat" to the Good Friday peace deal.
"Being a proud Ulsterman and playing for Ireland should not be complicated in the 21st Century," he added.
Cave also expressed dismay at the "very sad state of affairs" at Stormont.
'Consumed my thoughts'
Cave, from Holywood in County Down, has been capped 11 times by Ireland, making his last international appearance in 2015.
"After everything we've been through in Northern Ireland, can you imagine the most successful Ireland captain ever - Rory Best - having to drive through a hard border to play at the Aviva Stadium?" the 31 year old said.
"How is this good for my generation?"
Cave said he could not remember the Troubles but he viewed the Brexit deadlock as a "threat" to the Good Friday Agreement, which led to peace in Northern Ireland.
The UK's withdrawal from the EU had "consumed my thoughts of late", he said, and it "deeply concerns my generation as peace is all we have ever known".
Cave also commented on the impasse at Stormont, saying Northern Ireland's politics was "still in a dreadful place".
"The political landscape... is a very sad state of affairs," he added.
"I don't know how it is going to change as the Democratic Unionist Party (DUP) versus Sinn Féin saga rumbles ever on with the two communities entrenched on either side."
He said problems with issues such as healthcare and homelessness had been "ignored" since the collapse of the Northern Ireland Assembly in January 2017.
"For over two years our elected officials have steadfastly refused to govern," said Cave.
That meant that societal issues such as same-sex marriage and abortion had not been addressed in Northern Ireland, he added.
"What is so depressing is that during this very same period of time the global perception of Ireland, has been radically altered following the [same-sex marriage and abortion] referendums," said Cave.
"Gone are so many old perceptions and in their stead appears Dublin, this modern, multi-cultural society."