Being sad and depressed is a natural emotion. Even the happiest of people get sad and depressed at times. The difference maker is the ability to cope and recognize it's simply a call to action, a call for change.

"The hook-up" culture is a disposable friendship/relationship and I do find the concept sad, it is used to fill a long term need with a temporary solution and lacks spiritual depth they might actually be looking for. Sounds like a lot of wasted efforts, like using a band-aid when they need stitches no wonder they are perpetually sad. I consider myself an introvert ,I still have a few close connections that I have always cherished, it's just human nature. Having the ability to evolve thru the years with another human being is priceless and much more fruitful than a series of empty encounters.