I donít know why. But Iíve always pictured Shepard not knowing how to tie a tie. If he did, he always did a horrible job at it and Kaidan would always have to fix them for him. Worse off, itís their wedding day and Shepard still canít get it right. And go figure, he ruined his nice dress shirt by rolling up his sleeves. Way to go Shepard.
I dunno. Thatís my headcanon anyways. c8