First, never play at a table, on a site or in a room where you're not comfortable for any reason. Your feelings are reason enough. We all play better when we're relaxed, and part of that is trusting the house.

Second, learning to lose is a major part of playing poker. Some players talk about it, some don't. But everyone loses. Over time you'll run great, you'll run terrible, you'll run a little ahead, a little behind and everything in between. Over the long term, your relative skill level will determine your EV -- the cards will even out. Over the short term, the cards can make more of a difference. All you can do is assess your play -- is it just cards or are the other players better/reading you better? Are you tilting and not playing well after a beat? This is where it really helps to have a playing friend to talk things over with -- someone close in ability, so they'll be interested, who really wants you to win but isn't afraid to be critical.