At what point is playing out daily games considered abusive?

I'm playing someone in daily chess now where I have four pawns and a rook to their rook (completely winning position with no tricks that anybody could convert) and they won't resign, and now they have just gone on vacation (8 days remaining). It is not such a big deal but it is a bit annoying. Is their hope that I forget to make a move and lose on time? I just don't understand why someone would continue to play this out (haven't asked my opponent because they might take my comments the wrong way and become intentionally more annoying). What do you think, is this abusive stalling? 

I think you are wrong about your game. It is easy to see which of the three games you are playing that you are talking about. It is further easy to see that your opponent has 7 of 9 games on vacation and to realize that your opponent may have taken a break from all their games.

In any case, you won't have to wait all that long-- they only have 8 days of vacation left.

It is obvious that they are not intending to be abusive with their vacation but I mentioned it because I thought it would illustrate the annoyance that comes with players who won't resign in clearly lost positions. If the player had resigned---> I would not have to wait 'x' days. Regardless, this a minor point.

My opponent is playing on in a game where they have a single rook vs my rook and four pawns. While I highly doubt my opponent intends to be abusive, I feel there is a point where playing on can be considered abusive stalling. Is there a reasonable explanation to why anyone would continue playing in these positions?