Prime Minister Theresa May will not “trap” Britain in an endless customs union with the European Union after Brexit, her office insisted Friday amid growing unease in her cabinet and party that this might be the price of a divorce deal. Negotiations in Brussels have stepped up in recent days ahead of a high-stakes EU summit next week, with both sides seeking a breakthrough less than six months before Brexit in March 2019. May briefed selected members of her cabinet late Thursday on the talks, at which several ministers reportedly expressed deep unease at a plan to avoid frontier checks with EU member Ireland.