This confession had nothing to do with flirtation or coquetry. Stefan spoke straight from his heart and Mikołaj blushed hearing these words. He felt the same, but probably not to that extent.
When Skrzynecki was immersed in some activity, he could forget about Stefan even for a few hours. So he was a bit ashamed that he could not devote himself so much to him, but he excused himself to himself that Szwedas had been seeing men for many years, while Skrzynecki was still getting used to this situation. He went faster with some things, slower with others.
Stefan, however, did not seem to mind. He understood that Mikołaj needed time to get used to it all and gave him that time. It was very caring of him.