WITH DEEP PAIN AND REGRET, President Carter accepted Bert Lance's resignation. He was unquestionably right to bring this unhappy affair, at last, to an end. Pursuing it further could have brought nothing but greater grief to Mr. Lance, Mr. Carter and the whole enterprise of the administration.The President's explanation of his decision, offered at his press conference yesterday, was a model of dignity, intelligence and restraint.

Mr. Carter gave his friend - "a good and honorable man" - the warmest kind of endorsement in parting. Nothing that he has seen or read, Mr. Carter said, shook in any degree his faith in Mr. Lance's integrity. Mr. Lance is leaving because of continued "controversy" that impairs the adminsitration. Mr. Carter said once again that he sees no substance to the questions about Mr. Lance's conduct.But, of course, there is substance to them, and that is why the administration could neither control the controversy nor end it. In the end Mr. Carter had to choose between his original standards and Mr. Lance. He chose to uphold his standards.

One particularly graceful note in the President's public farewell to Mr. Lance was his absolute refusal to assign blame. Had Mr. Lance mishandled the mater? "If there's any fault there," the President replied, "it's mine, because of the requirements that I laid on him." Had Mr. Lance been unfairly drummed out of town by the Senate committee and the press? The President thought that the reporting had been fair, with some exceptions. As for the committee, Mr. Lance got an opportunity to defend himself fully in a formal hearing, the President said, and he was entitled to that. Now he needs to go home and take car of his business. Shouldering personal responsibility is not the least attractive trait in a President nor, in recent experience, the most common. To let Mr. Lance go had become unavoidable, but it could have been done in many ways. Mr. Carter, in the end, did it generously and decently.