Others think that the Italian brother's aren't so close to one another.
They always fight. They always complain about each other (Lovino more than Feliciano). They always hurt each other (no need to say who does this more). In short, they almost always never get along.
Antonio is baffled on why Lovino doesn't like his quite cute brother (and unknowingly adding more fuel to Lovino's jealousy). Ludwig is frustrated on why the two just can't get along (more for his sake really). Others are annoyed when their sibling fight turns into a sobbing session in the middle of the meeting (while amusing, it gets really tiring really fast). Some has approached the two (mostly Antonio and Ludwig) on why can't they get along better.
And when asked about that, both brothers will stare at the person asking, as if he was a stupid idiot, a stupid BLIND idiot. Then Lovino blushes in annoyance and starts to complain about Feliciano, while Feliciano on the other hand would say how much he loved his big brother.
Which is true. Feliciano loved his big brother a lot, and Lovino loves Feliciano too (which he would not admit unless you agreed to be shot by his Mafia and then be dumped along with the fishes). Some people just don't understand sibling relationships. Except, of course, the nations who has siblings as well.
Alfred and Matthew would understand. They fight a lot, but in the end they count on each other and enjoy's another company. Arthur doesn't see past the fights and the hatred Lovino emits, because he actually hates his brothers, period. The Asian siblings understand the complexity of how siblings operate. And so on.
While Lovino might rage and complain about Feliciano being an idiot, he calls him that out of habit. While Feliciano might complain about his brother's laziness a lot, he's gotten used to it, along with the punches and headbutts Lovino throws at him sometimes. Lovino has understood long ago that Feliciano was better at him at some things and more liked by the others, but then that doens't mean other nations should start saying it within his earshot. They actually do some bonding time, agree when it comes to their cuisine, and care for each other. And while they might fight, bicker, and generally seem to hate each other, they do truly love each other, and hold a special place in each other's heart- since after all, they're siblings.
Besides, la famiglia e importante sempre.