I see your point to a certain extent however would this not be the case with any partner he chose? Its the same in all reincarnation stories the one who reincarnated is mentally older then everyone around them this one he wants what he didnt have falling in love and human connections is just 1 part of that and at least they seem to be amicable and its not being forced and it would seem from my point of view song would be loyal to him what other choices are there atm the indoctrinated child warrior or the crazy scientist who chose to be caged and willing to do evil for whatever reason oh but there's his old childhood little sister who's now a grandma maybe she's the better fit??
I dont think it will be heavy on romance its like the author put in it as a filler or maybe a comparison to remind you who he was and now is its just background noise to the main storyline. It doesnt bother me personally but we all have our pet peeves feel free to recommend some others simular to this I mainly find harem ones or yaoi some ones without would be great!

i love this story but honestly the love line between the mc and fl puts me off--knowing that the mc is an older man and fl is waaaaaaaaaay younger than him. i cannot stomach their love line.