<p>The Voldemort made DD a horcrux theory is completely wrong, no offense. It doesn’t make sense at all. What makes sense is that Snape is good and killed DD under DD’s orders. They knew Malfoy could not do it. Thus Snape would have to (because of the vow, which he told DD about) or else both DD and Snape would die. DD was already weak anyway (shows why he was preparing Harry for his death the whole year and why he was so keen to take the potion the night of his death) and knew that Snape getting closer to Voldemort and also gaining the trust of everyone was much more valuable. That’s why they had the fight in the forest (DD was telling Snape he had to kill him, Snape was saying no) and also why there was hate on Snape’s face before he killed DD (he hated what he had to do).</p>