Based on my weekly Shabbos drasha in shul:
B/c of Kamtza and Bar Kamtza, Yerushalayim was destroyed.
What did Kamtza do wrong? He wasn't even there?
1] Maharal: The Gemara says tha Kamtza and the host were friends. Back then, people weren't friends for the sake of friendship but in order to garner power to fight against people they hate. Kamza was part of that culture.
Today this is called "factionalism". [כיתתיות]
Today you have Litvish groups against Chasidic groups and vice versa. Litvish against Litvish. Chasidish against other Chasidish groups. Then WITHIN the groups themselves you have battles [Two Satmars, two Bobovs, מחבלים vs. שונאים in Yeshiva X etc. etc. etc.]. Amazing how Klal Yisrael doesn't learn the lessons.
2] Rav M.M. Shulzinger: Kamtza should've come w/o an invitation. Why did he stand on ceremony?? Go to simchas b/c it will make the Baal Hasimcha feel good and not based on how YOU feel about it. Leave your ego out of the picture. Life becomes much simpler when we let go of our egos.
Ir Miklat - we send the Rav to the Talmid and vice versa b/c the Torah says to give him life and there is no life w/o Torah
תלמיד שגלה לערי מקלט, מגלין רבו עימו: שנאמר "וחי" (דברים ד,מב; דברים יט,ד; דברים יט,ה)--עשה לו כדי שיחיה, וחיי בעלי חכמה ומבקשיה בלא תלמוד כמיתה חשובה. וכן הרב שגלה, מגלין ישיבתו עימו.
What abt. a friend? או חברותא או מיתותא? That is ALSO life???
Pnei Menachem: A friend shouldn't need the Gemara to tell him to go. If he does - he is not a real friend anyway!!! Go w/o being told. Be a real friend!!
I remember that there were many people whom I invited to my wedding [27 years ago minus abt. 2 weeks] and they didn't come [a lot of empty seats at the tables]. But I especially remember one fellow I didn't invite and he told me he is coming anyway [to be משמח me] - and he did!