There's a certain peace of mind that comes with knowing how long you have left to live. The doctors made it clear, after all: his leukemia was discovered way too late to be treatable. At most, Ren's got around 3 months left in him.
But Ren certainly doesn't have to let anyone know about that, least of all his friends. Plus, if there's anything Ren's good at, it's putting on a mask and acting as if he's just fine. Because, really, it's not the end of the world if it's the end of him. Goro'd probably disagree with him, but...
... well. That's the reason Ren's up at 11 PM, rounding the corner of the Akechi family residence to knock on his boyfriend's window. "Hey, Goro! Come outside, would you?" He whisper-shouts through the glass, feigning a bit of impatience. "If you're not gonna respond to my texts, at least go on a walk with me."