a e-relationship is 'dating' through online sites (Facebook, habbo, World of Warcraft, runescape, etc) And though most sites do not promote it, most have no ban on it.
an friendship can become more when one asks the other, in most cases it no more than that, but in others, one partner may want more.
I would not advise it as often it ends badly and you shouldn't trust someone over the internet.