Before Lyra came into the picture, Galen and Krennic slept together all the time. They told each other it was just a convenient arrangement between friends, but Krennic was utterly in love with Galen from the start.

+ drunken party makeouts/hookups
+ Krennic constantly teetering on the edge of admitting his feelings, but not willing to complicate their friendship
+ Galen being utterly oblivious no matter how obvious Krennic is being, missing the clues even when Krennic is trying to give him hints
+ Krennic's downward spiral, drama queen, train wreck reaction to Galen telling him "So I met this girl..."