It was a one-sided love affair.

From Indigo Scanlations:

Ryou, who has always admired his deceased father's best friend and doctor, Kougami, decides to confess his love after he becomes a university student. But somehow that disastrous confession ends up in them dating?! A smooth sailing love story sinks into rocky waves since the only thing Kougami talks about is Ryou's father, Shun.