Driver one is traveling south on rt 128, in front is driver two also traveling south. Driver two turns on right directional to exit off highway. Once realizing there is no exit at that point driver two without directional enters back into ongoing trafficin front if driver one, causing driver one to rearend driver two. Who is at fault?

Driver one is at fault for following to closely and rear ending. He should have noticed what was going on in front of him.

Depending on your State and comparative negligence I would say 25% driver two and 75% driver one. Just because you rear end someone does not make you 100% at fault. The argument would be made that there was no reasonable expectation on the part of driver one that driver two was NOT simply pulling over; no reason to believe driver two would pull back into traffic. Also question of attempting to avoid (was there another lane driver one could have pulled into, braking, blowing horn).