You clearly haven't been watching the news at all. MSM especially was never pro-Trump this cycle. In fact, they ran many hit pieces against him. Cruz got demolished because he relied on things like debates to get national exposure while Trump generated his own publicity by saying outrageous things. After the debates stopped, Cruz started to fall into obscurity. The media spent so much time airing Trump and his outrageous statements because it glues viewers to the screen and generates higher ratings than any other candidate of either party.
Pretty much every news outlet will admit at this point that Trump has manipulated them like nothing they've ever seen before.