@Abetillo—
That reaction is somewhat relevant, but there is no point to a learning experience
as such if one cannot apply what one has learned to
a different situation. So it seems that Shouta's father did not see Lucoa as Shouta's
life-partner.
@Xer0sama may have been writing tongue-in-cheek (I cannot know), but I think that, at this point, we are to infer that, indeed, Shouta and Lucoa will be partnered for the rest of Shouta's life, and will become sexually involved and sexually exclusive when Shouta is older. (Shouta is already romantically attached to Lucoa, whether he acknowledges that or not.) If Dad has come to realize that, then
@Xer0sama's question has some answer. If Dad doesn't realize it yet, then
@Xer0sama's question becomes one of how Dad will react when he does.