Speechless

Another colleague leaving the company as he finds it tough going. I'm with this company for about 6 months and so far 4 colleagues have left. It saddens me. It puzzles me that I'm sad. Why? Why am I sad that people leave for greener pasture? I've been on good terms with them but our friendships, save one, isn't really that in depth. I don't know whether it's pre-menopausal symptoms or what but I'm really becoming sentimental and emotional nowadays. Argh, one more colleague leaving, I'm sadden whenever one leaves, like I've lost something... I wish them all the best.