Feeling depressed

I feel so depressed when I'm alone , sitting in a public place , no phone no friends or family around just makes me feel lonely and depressed. Hearing couples together having a good time while I'm just sitting down alone just made me have the most horrible feeling ever .... I went out with my Bf he was playing Pokemon go and I just felt like he was playing it alone and I was just following him around which I did not want to do so I just walk away and sat down somewhere he didn't come looking for me until an hour later.....