playing alone is indeed boring. The problem is the higher level you get, the less people there are to party and as you get 50+ UM each individual becomes quite strong, to the point where each one can stand alone without needing to party (most classes). That plus people have certain groups they want to party with and don't seem to party random strangers anymore. Also we are from all over the world and it can be hard to coordinate being on at the same time. And let's not forget since you usually take an exp hit when partying people don't like to give that up for someone they don't know. and/or don't really "need".
I used to enjoy playing solo. I played a mage in NM and found it frustrating to be totally reliant on parties. So when i hit HM i made ranger, archer, and combat defender. It was a breath of fresh air to be able to level up when i wanted to and not wait around for parties. But now, as a UM archer it's easy for me to solo (though it's actually faster exp if i duo with another archer or higher level - of course) but I just don't care about that anymore. Over the course of 10 months i've played around 9 different toons, and i've probably soloed over 300 levels. As it seems you know, It's boring and lonely to be solo all the time, and in the new pvp maps if you're alone you may as well just lay down when the opposing faction comes through and as always you can't do anything by yourself in pvp.
As you've seen shaiya quickly becomes boring and seems pointless when you play too much alone. It's the social aspect that is it's greatest strength. After all, it's a massive multiplayer online game. it's meant to be played in groups, not solo. It doesn't exactly have an engaging storyline or exciting quests to do. for the most part its grind and develop your character and then acquire gear and then pvp. To succeed to the fullest potential in any of those tasks, you need others help. you can't kill bosses alone, you can't get the uber goddess gear alone, you can't, even with the highest stats and gear possible, succeed at high level pvp alone.
Just try to find a group of people you like. if you can't find something fun about the game, don't force yourself to play, it doesn't work. Also try a bigger guild. As you said, if it's a smaller, guild you may as well be solo when nobody is the same level to party with.