I guess it's the anxiety and tendency to overthink when their loved ones is involved. Because his opinion matters too much to them, so they're scared of any negative reaction.
There are two ways to day i car one equals i understand this is and important and emotiknal thing but it doesnt effect my feelings about you
And the other is indifference, lucas worry isnt that it wont matter to him because he doesnt actually care about them. He doesnt have the same perspective on how hard it is for Ml to express love the judith does. The reason he's been so cold is because while he loved his uncle and thought his uncle loved him after his death he convinced himself he was just going through the motions and didnt actually love him.
i was so confused of their reaction of ruediger's response if he found out her secret. they were complete strangers before this. ruediger didnt know the aunt before she transmigrated. the only version of the aunt, ruediger knows is herself so what the fuck would change if they know his reaction would be he that doesnt care. every other manhwa i've read the FL felt happy or relieved once the ML finds out and his response is he doesnt care. some novels even have the fl transmigrate when the OG body already did cruel things to people including the ml. So i dont understand luca and aunt's reaction