Man does not experience reality, he interprets it. He compares what he observes to what he expects, and he acts based on the outcome of that comparison. Reality is only a reference point, and a relatively minor one, as man will act to change the world around him (i.e., reality) to meet his expectations before he will question those expectations.
Thus, if you set and manage a man's expectations, you define his reality.
In this sense, there are two realities. The first is the physical world around us and is not open to debate or philosophical meanderings. It is what it is, with or without us. This is what I mean when I say, simply, "reality" without a modifier, e.g., "a" or "his" or "ours." The second is our vision of what the reality ought to be, i.e., our expectations. This is what I mean when I ascribe reality as belonging to somebody, i.e., "his reality." Generally, though, I don't think of the latter as "reality" in any sense, and I tend to refer to it as "expectations."