There are two great things about To love ru.
1. There were a huge number of h doujins for it long before any anime was announced.
2. The vast majority of the doujin artists seem to share the opinion that the correct choice for Rito is both Lala and Haruna. Seriously, it seems to be very rare for any doujin author to support one girl and not the other. They seem to insist that it can only end in a threesome.
Apparently harem end is the correct end. Now the actual manga creators need to get the memo.