I think a pure text chat is insufficient when it comes to showing emotions. However, nowadays we have video and voice chat too, not to mention phones. It's still not a lot compared to real physical interaction.
I'm not saying it's not real luff when it's purely online, I'm just saying that it's hard to express all your emotions through text. It's easier when you can hear the other persons voice and see her, but still far from the real thing.
I sometimes call people i know online just to hear their voice. That way, I feel closer to the person, cause he or she is more than just words on a screen, I've got a voice to go with it aswell.