Mic was always close to the actor.
That doesn’t mean much. Proximity matters, but angle is just as important. And in a room that reflective, the type of mic used is pretty important. Was it a shotgun? Terrible choice for a room that is all hard surfaces. A hypercardioid would have been better, or lavs planted on the actors.
I think another problem was that we shot this in a very echoey, white room. I don't have too much sound experience. I thought the best move would be to turn down the recording sensitivity to pick up less echo. I figured the male lead would be delivering his lines softly anyway. Combination of bumping that up with a loose cord, caused the problem.
Turning it down to “record less echo” means you’re recording less of everything... including the stuff you want. Soft dialog needs to have a close mic, a tight pattern, and detailed attention to pickup axis. Low record levels are hell in post even if you don’t have a loose cable causing problems.
You can mitigate reflections in a room like that by hanging sound blankets over C-stands off-camera. Hang them away from the walls to create a buffer space that will help deaden the refflections. It adds some time as you have to move the blankets every time you move the camera, but it’ll tame the room and make sound recording easier.
And again, if you’re not wearing headphones and listening as you record, you have no idea what you are or aren’t recording.
I think this short can still be saved. It’ll take ADR and some pretty intense sound design including Foley and sound effects editing. Those can be challenging, but they can be fun as well. Everything else above is “lesson learned” to help you on your next projects.