I can safely say that the biggest deciding criterion for whether to ally with someone or not and in deciding whether to stick with an ally that I've found myself using in my admittedly short time on this site is the quality of communication I am getting from them. I suspect this is a problem with newbie games in particular here, and seems to be a problem you may be running into yourself. Communication is a way to establish your credibility, and avoids leaving a player in a situation where he stabs you because he isn't sure what you're up to and is positive it can't be good for him (honestly, probably my most common reason for stabbing in games I've played here so far).
I also took a look at some of your games, RA, and a number of your outright defeats had their beginnings in some 1901 and 1902 misplay. I obviously can't see any of your active anonymous games, but bad early blunders can really cost you.
Also, and many other posters have already hinted at this: many of your games seem to be PPSC games, and this little change makes a huge impact in how people approach and play the game. I think the site here bills PPSC games as newbie friendly, but I think this is misleading. Once there's blood in the water in a PPSC game, there is generally little incentive for moderately strong powers to side with struggling powers to contain very strong powers. Often, it benefits them as far as the score is concerned, to jump in on the feeding frenzy and help the big power win. So once you start stumbling, there's much less chance you'll be able to buy yourself a diplomatic reprieve and get back in the game.
Also helps to just relax and accept that some people are going to do awful things that are terrible for them long term, sometimes you will draw Austria and Germany will be playing his very first game ever, and think you're his best target, and sometimes there is nothing you can do about it but relax, take a deep breath, and go on to the next game.