He knew that people didn't like it.
He wasn't quire sure, because Luna Lovegood was the most beautiful person he had ever met, and he loved every fibre of her. But he knew that people didn't like her, and that the silly looks they gave him meant for him to be scared. Even his gran didn't really like it, and she snarled occasionally at Christmas dinners, but quietly, because after everything, she had decided (very very begrudgingly) that all right perhaps Neville could make decisions for himself.
Quite honestly, he could not care less.
Because when he was with Luna Lovegood, everything in the world melted away, and he did not give half a peony's worth of thought to anyone. (Half a peony, that was the sort of thing Luna would say, and that was not the thing he would sort of say, and he was absolutely delighted about it.) All he knew was that when he was with Luna, the world was sunshine; not made of sunshine but actual sunshine, that was all that was. And there were flowers growing out of even the sad places in him, and there was bravery in places he never thought there were before, and he was better, somehow, a thousand times better.
And they laughed and talked for hours on end, their conversations swinging from one topic to another with wild abandon, and sometimes they would go on fantastic adventures all over London or even just tiny little adventures in their back garden. Everything about life was an adventure when Luna Lovegood was involved.
So to be quite honest, Neville Longbottom simply did not care that people did not like it, because all he really knew, at this point, was that he loved Luna, and that Luna loved him, and that was all that mattered. Their love was theirs.