No offence, but Arias hasn't lied about everything. She has bits of truth to make her testimony sound believable, but she hasn't lied about everything.
There is a lot more proof to say they had a sexual encounter that day vs. that this was staged to look like it. Physical evidence in terms of the photos and the visible fluids in them, the gynaecologist report, the fact the the photos taken were attempted to be deleted permanently, they confirmed through the phone tape that they had sex before, and there were other photos that did show them in compromising positions but they were ruled inadmissible, most likely due to being too prejudicial.
I'll just leave it here. Because I think this issue just boils down to a matter of perspective, and that won't change, seeing as everyone just appears to be taking the same evidence of proof of their own respective opinions.