Joseph
Have you heard of 20 Sivan? Erev Shabbos Parshas Chukas “Zos chukas Hatorah”?. google them. This idea that we dont mourn on other days aside from Tisha B’av is demonstrably false. As is the idea that we dont mourn during Nissan. (I am scratching my itchy face much like any avel as I type this)