Online relationships are just the modern day penpals. You can get to know the person online but you are only knowing what they tell you, to actually have a relationship it really needs to be in person so you can make your own judgements.
It's not senseless. But it's not easy, either. If it is only based online, though, there are other sets of challenges to consider and you'll need to be honest with yourself about them. Do you see the person offline at all?