Look at the diagram on
this previous post of mine. If I remember the whole thing correctly (it's been a while since I last played the game), and I think I do, to get the harem ending, you want to go for the perfect end. So, according to the information provided there, which is accurate, you need Tracy to survive (which it's the only requirement for her to be in her positive state) and have the rest of the characters, including Marcus, also in their positive state. You have the conditions to make every character positive listed on the left column of the diagram.
If you fail to get the harem ending, then you've missed one or more conditions along the way. Believe me. I've been there before. For example, the last time I played the game, I failed to get the harem ending at first, and I was sure that I had done everything correctly to get it. But I did not actually. In my case, I thought I had chosen to watch the romantic movie with the mom of the MC, but in fact I had watched the porno. And that mis-step broke everything. You need to be careful to meet all the requirements with every character to get their positive state to achieve the harem ending.