The article mentions it may be a love 'rectangle'. If that's the case, I could totally see it in a way which has Tony and Pepper playfully teasing each other
Or it could mean that Pepper and Happy are hooking up. It happened in the comics.
I know it happened it the comics, but it's not believable in these movies. There has been ZERO built up to Happy having the hots for Pepper in the two movies. It has always been Tony and Pepper with the exception of Tony in the fling with the reporter, but that was before they started their relationship.
Also why the hell Pepper pick Happy when she already has Tony? That's too unbelievable.