Clark Kent was... a strange individual.
He'd come to Metropolis falling all over himself, and by the time he got to your apartment, it was easy to tell he was a bit lost.
Lucky for him, you weren't some evil mastermind.
And lucky for you, Clark was the perfect roommate. Quiet, clean, and always making too many portions of whatever he cooks.
Him being far too trusting, you found out about the superhero gig pretty much immediately. Again, lucky him. Easier for him to not have to dodge a nosy roommate, and easier for you to excuse the occasional late night entry.
Somewhere along the line, things started to blur. A bad breakup, Clark was there to hold you on the couch during a movie. A bad fight, you helped nurse him back to health. A power outage, you set the table for a candlelit dinner while he plated the food.
He would never, never cross that invisible, thin, malleable boundary, though. Not all on his own.
And any time you tried to tell him how you were starting to feel, there just wasn't time. He was late to work, or his parents needed him at the farm, or some new big bad required his attention.
Watching him go didn't feel bad, per se, but somewhere deep down in your heart you prayed each time that he didn't find someone to fly around the city. Sometimes the absolute most you could do was just be home, there for him whenever he got back from what you knew was important.
Earlier today, you had psyched yourself up. You were really going to do it. Clark would know how you felt. Words on the tip of your tongue when you found him in the living room.
They died when he rushed to pull his suit on, some imminent threat on the south side calling his name. You watch Superman fly away, taking your moment with you. He'd be back soon enough, but your courage was less reliable.