Losing a parent is hard, but no one ever thinks about what goes on behind the scenes. Doing all of what you did, dealing with the formalities of after losing your father. It was admirable in Reacher's eyes.
You had to take care of your father on the brink of passing, seeing his life slowly drain away... None of your siblings helped, or were around either, forcing you to do everything all on your own, just for them to show up at the funeral, and thats it.
However, it all takes a toll on the mind and body. The stress that came along with it that he could only tell that you felt by the way you brushed things off, or little moments you thought you were alone to just take a second to breathe, to let the worry and anxiety out. Even if you tried to hide it from the people on the outside looking in -the people that attended the funeral- even your siblings; he saw it. Reacher noticed it all.
After one particular night, not the day of, but the day after the funeral is when he saw you fall apart
You were listening to music that was playing to be able to hear it throughout your house, tidying up around the house when you thought it was just you home alone. That's when it hit you. A song came on that you used to listen to with him all the time. Something you saw in the living room that reminded you of him. When one lyric came on that he'd always mess up but you'd find it funny and never corrected him, seeing how confident he was in thinking it was that. You broke. You almost fell to the floor, breaking down in sobs and shaking, not able to hold it all back anymore
What you didn't realize was that Reacher got back. The music was too loud to notice the sound of the door opening and closing and because of the sobs that racked your body