He absolutely could be a sap and half the time it wasn't even intentional. Diluc is just a man in love and it shows, and why shouldn't it?

"I don't think it should be too difficult to align our schedules," he says, smiling up at the other man as he keeps Kaeya's hand near to his lips. "We have a few things to do around here, but nothing so urgent that it can't be put aside for an afternoon."