I can relate to the feeling of loneliness. I used to suffer from it and had some depression about it. Over time though, I thought about it as I always said that I wanted to be at parties with a lot of people and with a bunch of friends even though I only have very few and then I realized that even by my lonesome, I'm still a somewhat happy person regardless. I look at people who hang out with a bunch of others and go to tons of parties and I think I want that for a second but then I realize that firstly, I don't like parties, I don't like crowds, and I don't like noise, so what's the point?
As far as tonight, I'm actually alone at work currently as I work Swing (Evening) Shift on Sundays. I don't mind it too much personally as it affords me some more alone time. I talk to my coworkers and what not and we get along but I know what you mean by the feeling of loneliness as I never really get invited to anything outside of work or really talk outside of work with anyone here due to lack of common interest and the fact that I work whenever these events happen as I also work Saturdays in the evening. It is what it is to a degree. I don't take it personally as they know that I work so it can't be done anyway.
In the end, I kind of stopped caring though. I cared through high school and some through college but I've been stabbed in the back too many times to care anymore. I have acquaintances, colleagues, and what not but only about one or two real friends I can count on (not counting my only family, my parents). Those experiences have made me a really frigid and uncaring person. As it is, I suck in dealing with emotional situations and now, I just try not to get involved. Whereas others openly tell their life stories and hang out without thinking twice, I like to keep an arms distance at least due to the past. Over time, I'm sure I'll become more trusting but it's hard after being screwed over so many times to have any trust in humanity. And as it was, I was a somewhat distrusting person so that only exacerbated the issue. Most people don't have any idea that I'm rather lonely as I don't really show it or talk about it as it's not pleasant to deal with and no one else's business in the end.
But yeah, I can understand the feeling of loneliness. Sometimes, I feel sad about it and want all these friends and people to hang out with but I think about it and think about how much I like my life the way it currently is. I get to relax when I get home and devote time to myself and I think to myself, "do I want friends because I genuinely want people to hang out with and have my back or do I want friends just to fit within the norms of society?" For the most part, I realized I just wanted to be in the norm of society rather than because I actually need or want to hang out with others after work. Don't me wrong, sometimes I do like to catch a drink with a few friends from work but for the most part, I prefer just to go straight home. Though one of the issues I run into is the fact that I don't drink any alcohol and some people simply not liking that.
The way I see it though and my dad always says this to me, "Don't worry, there's always someone out there for everybody." Considering I'm in my early 20s, I'm not too concerned as of yet. The way I see it, I may be alone but at least I got my health, got a roof, and am genuinely a happy person. Sure, I have feelings of loneliness at times like I said but I am genuinely happy with what I have. I have a nice job, a business, a family that loves me; I have very few friends but I deal with it. I get asked by my parents sometimes if I am truly happy and I tell them I am because it's the 100% truth. Even with my bit of loneliness, I just make the best of it and do what I can to pass the time. I take on some projects at home to have fun, play some golf, cruise around in my car, gaming, I have fun in general.
If you feel lonely and depressed in general, you can always try going out and having some fun doing something you enjoy, it may at least lift your spirits. And if you want to chat, there are plenty of people here including myself who would enjoy chatting with you. This post ran kind of long but the main point is that even if you feel lonely and somewhat saddened by that fact, the point is not to let it keep you down but instead take that and think to yourself "what would make me happy" "what would I want to do". Find something that you enjoy doing and then do it. And if you just want to talk to people, you can go out and talk to people, talk to your family or friends or even here online with others, there are plenty of people including myself willing to chat tonight or pretty much anytime to just shoot the breeze.