Wow, I never saw this response, I'm sorry for the late response, Chloe.
As far as online relationships being only a friendship to me.... No. They cannot. Friendship requires trust, trust requires intimate knowledge of the other person. That requires a real life component to the relationship. I'm sorry, Chloe, but to use you as an example for this, if you were to message me every day for the next 20 years, you'd still only be 13 characters in my inbox. Although, I'm certain, if it was such an extreme amount of time I'd have built some amount of trust, but without actually meeting, the only thing for 100% certain I'd know is that when I met you you were not an 80 year old creepy stalker person. Maybe I'm just a cynical bastard, but I believe all people are liars and thieves waiting to strike and hurt you the best they can. This doesn't mean they can't be nice, friendly, or kind, but they are predisposed to pain and suffering and causing pain and suffering.
To continue this point, even though it is very extreme, if you and I were to have an encounter somewhere, you suddenly became real and earned about 12 years worth of the trust that was building. When things become real, in my experience, they become accelerated due to online interaction, if the online interaction was not immediately proved to be full of false pretenses and lies.
Anyway I've strayed from my topic. I still believe that online relationships without a real component cannot work. There must be a real component or the relationship is as weak as dust in a hurricane. If your needs are satisfied by a little white square with black text, there is a serious problem, and you need serious psychiatric attention.
Next, I'm not saying that personality and expectations are unimportant, I'm saying they are secondary to trust and honesty, in all relationships. The reason people have more than one relationship of any type is because it is not apparent for a few months what the other person wants out of the relationship. The relationship is a means to get that information and understand the person, but it won't work without trust and honesty between you. I'm not saying little white lies, lies of omission, or anything like that are the ending circumstances of a relationship. Sometimes they are useful, sometimes necessary, sometimes they are huge problems. The determining factor is what the other person thinks they are, and if they forgive you.
Finally, back to the "well hidden moods." It is not impossible, or even hard to maintain hidden moods. Maybe I have too much experience, but the simple way to do it is adopt a writing style for each type of encounter. I have never, personally, been able to break myself of that. I naturally step back when I get angry, look at the situation, think about it, and reply in an appropriate tone. There are several default cases, criticism of me, curiosity, cold logic.. etc. Often people mistake the tones for things they expect to hear. When I get into "philosophy" mode people think I'm angry because it is a mixture of curiosity and cold logic. They misunderstand it as "Oh God, he's pissed" and treat it according to how guilty they feel, or how angry they are. To catch someone's proper mood you must know them well enough to know how they react to things, and you must understand what they feel about what you said. Without meeting in person, I find this to be the most difficult part, and because it is the most difficult part, it is the part that has the most problems/errors associated with it.
I'd love to continue rambling, but I've got to get to work. I'll wait for another reply.
Ciao.