How is it that I can't seem to remember opening-theory?

How is it that when playing turnbased games, I play a lot better then when I play a game in real life ?

How is it that I'm somehow afraid to loose when playing in real life ?

What is the solution to start playing better in real life. To actually remember opening theory and not get blown away by people who seem to know all the details ?

I'll take a stab at a few, given that I've experienced a few  of them myself:

How is it that I can't seem to remember opening-theory?

This usually indicates that you're playing very few slow games in said opening. You tend to retain  patterns better when you give yourself time to burn positions into your head (usually happens more when you can afford to take your time per move). Note that this is SLOW OTB where your primary focus is always on the board and cannot be compared to online/correspondence chess.

This may also indicate that you've not been playing all too long ... the more experienced you are in an opening system, the more likely you've have "opening anchors" deep within the opening lines, as opposed to being "out of your book" on move 2 or 3.   It's like you're not even "forcing" yourself to remember the lines, you just "know" them out of muscle memory.

How is it that when playing turnbased games, I play a lot better then when I play a game in real life ?

Easy. No nerves/pressure, you can concentrate on the board when you "feel" like it. If you feel your chess brain is "running at peak performance"  from 8-12 p.m at night, so be it, that'll be when you probably log on to chess.com .  Now you can't always  demand that real chess be played when your brain feels it best. :) Also => Access to opening theory and analysis boards. Plus with turn-based games, you are less likely to be psychologically swindled or walk into a trap. Finally,  you can grind and analyze really deep into positions in turn-based games.  With real games, you have to play the best move in accordance to a time-budget.

How is it that I'm somehow afraid to loose when playing in real life ?
The ego is way less fragile online as opposed to face-to-face situations. Just take a look at the readily available sampling of  flame-throwing trolls  in the forums who are mighty brave to take potshots at people when they are  hiding behind their computer screens.

One's risk-taking tendencies tend to drop in OTB situations (especially tournaments) or fear of ridicule (losing to a 6-year old girl in a OTB game).

Often enough, people pay too much attention to the rating (both theirs and the opponents) and play according to some self-fulfilling prophecy (I will ALWAYS beat him because I'm rated higher or vice versa)

What is the solution to start playing better in real life. To actually remember opening theory and not get blown away by people who seem to know all the details ?

At first: thanks for your input!

Well, I think that a lot of what you've stated is "to the point" in my case. Maybe one point that is also a "problem" in my case: decisionmaking. But that gets awfully close to fear I guess.

I'm usually very cautious. I don't want to make dumb mistakes. Which I allow myself when playing turnbased games (coming to think of it), since my online rating is more "virtual" than when I'm playing at the chessclub. That's one side. Maybe another is judging the situation correctly: I often miss the "good moves". I can build up a good position, no sweat. But then. From a better position win the game. That's where I often go wrong. F.e. going for a mate-attack on the king and ignoring possibilities on the queenside. Maybe to hasty ? Afraid to miss the good moves ? Might have given the correct answer already...

Any more advice on that subject ?

NM Heisman has a lot to say about this. This article might be of interest to you

http://www.chesscafe.com/text/heisman13.pdf

Plus, what  my own coach is trying to help me with  may apply to you. A skill stronger players have that weaker players don't is "squeezing" the win consistently.  

My own bad habit was to win a piece or two pawns and look for a quick take-down : Though most of the times, against strong players, you have to be PATIENT and be more of a slowly crushing boa constrictor than a tiger.  Winning with small advantages is an art by itself and more often than not,  you have to "let" the win come to you by playing simple uncomplicated moves that improve your pieces, eliminate counterplay and not force the issue unless you have a compelling (forcing line) that buries your opponent even more.  As my coach says, your opponents will often beat themselves.

This really helped open my eyes to how a won game is won.

I think I'm going to read that article of Heisman. And think a little about your input. I'll get back on it! Thanks.

Well, I recently won a game (first time this season) at the club. I didn't play the opening too well (made an error), but could recover from it by keeping cool. Slowly got a better position. And then, well, an error in judgement from my opponent allowed me to win the exchange. Then the hard part: I won the exchange, but my rooks were not "in the game yet". Furthermore, my opponent had all his minor pieces attacking my kingside position. Because I had read most of Heisman's article earlier that day, I understood I didn't have to win the game fast. So slowly I started pushing back his pieces. Than a "non-optimal" move made by my opponent allowed me to let the rooks enter the game. A few moves later I could mate him.

I didn't play brilliant. But keeping cool and being patient made me win. Thanks for the article!

My last game, I applied the same rules. Didn't win, but afterwards I noticed I missed the win. Maybe a little afraid for time-trouble (had less than 13 minutes left). Somehow I tried to avoid the risk of loosing. But I lost anyway. Half a point that is. Better luck next time I guess....