*i've been loving you for quite some time*

ML has been in love with the FL since long before the present timeline (includes BL). It can also be interpreted as unrequited love or secret crush. More specifically, the list includes three instances:

1. ml and fl used to be lovers but for some reason, the ml is the only one left that remembers their love, so a new love story starts.
2. ml has always loved the fl, but the fl did not know of his existence until the present timeline.
3. ml has always loved the fl, but the fl was oblivious to his feelings until now.