Britain don’t want to pay tarrifs

According to a recent interview with Simon Coveney on the news, Britain won’t agree to any border infrastructure on the island of Ireland. Considering Ireland has agreed, and according to the interview fine gaél have, where is the eu border going to be? Is Simon talking about a British Ireland? In the same vein, if northern Ireland are staying in the single market but only the single market, doesn’t that mean there should be two border checking points, one between northern Ireland and Britain and one between the north and southern Ireland?