So my boyfriend is muslim, I am not affiliated with any religious beliefs, I consider myself spiritual. We both respect each others beliefs. Sometimes when I ask him questions about his religion, he doesn't know how to explain it, so we often look online for answers. One question that I have that I could not find an answer to is why do muslims shower with underwear on? When we shower together, he doesn't wear anything, but he says when he showers alone, he wears something. Explanation please?