@Rozzak If the bf has a panties fetish, probably not, all of that would be exciting to him. (There's a lot of guys out there that buy worn panties from women and pay extra for skidmarks. Fetishes can be really gross to those without the fetish.)
If he's doing it because he likes making her run around without panties under her skirt, he'll
definitely not get bored with it. Since he ran away, forcing her to chase after him like that, I think that's what he's after more than her panties. He likes her being embarrassed and potentially exposed.