Well it's not the first time that 1D stole melodies from other songs
UHUM *Best Song Ever*, *Change My Mind*, *Rock Me*, *You & I*, *Little White Lies*, *Why Don't We Go There*, *They Don't Know About Us* UHUM
They did it loads of times already sadly enough, I wonder why no one sues them actually.
They've done this a few times now. I don't think there's anything wrong with it and I don't think Hayley cares that much either, she's just putting it out there.