even though william became finley's grandpa at some point, it is in their memories that they held those romantic feelings for -- not while they were actively grandpa & grandson. plus finley didnt even remember their past until william (as his grandpa) passed, & even then, it was still mourning the past. as for william's pov as a grandpa, it was shown he denied himself of ever acknowledging any romantic feelings because it went against his pride and duties. it wasn't until this timeline & this finley's confession that he was ever able to realize & acknowledge his romantic feelings. i mean, he even rejected finley's confession at first! instead of just thinking "grandpa & grandson", try some critical thinking