You probably already figured this out, but it seems like the game is designed so you set the relationship as "Dad" or the text doesn't make sense. If anyone else figures out a different word to use, let me know. I Tried Boyfriend but then the sentence "At least Boyfriend is here with me" doesn't make sense. Maybe "My Boyfriend" would work, but probably not forever.
Viewing post in Lewd Island [xRed Games] comments
The relationship between the characters in Lewd Island is not defined.
It is up to you to pick what that relationship is and interpret it in your own way.
This is why we had to adjust certain dialogue lines so any of your possible choices could make sense and why certain lines just sound better than others.
The relationship between the characters was not intended to be incestuous, and we appreciate you pointing out potential misconceptions.
We will see what we can do about this.
Thank you!