For Theodoric, the main character of "The Mouse," written by H.H. Munro (who was also known as Saki), anything that presents even the slightest bit of discomfort represents "the coarser realities of life." It is clear that his mother, "whose chief solicitude had been to keep him screened from what she called the coarser realities of life," raised him so that he did not need to deal with any discomforts or inconveniences. Therefore, after she dies, he struggles to deal with anything that presents the slightest difficulty, including harnessing the pony that will bring him to the train station.
Mice certainly fall into the category of "the coarser realties of life" for Theodoric. As Munro writes, "Without being actually afraid of mice, Theodoric classed them among the coarser incidents of life." Theodoric feels that mice are dispensable and that Providence should have gotten rid of them a long time ago. Theodoric extricates a mouse from his clothes to his great consternation and embarrassment, as he is sharing a train compartment with a fellow traveler. He does not realize until the end of his journey that she is subject to far more than "the coarser realities of life," as she is blind. Therefore, he has worried for no reason, since she did not see him extricate the mouse from his clothing, and she has far greater worries than he does.