Will To Love-Ru season 3 ever come out? Nobody really knows... Even though Season 2 (Motto To Love-Ru Trouble) mostly covered the manga, a new on-going manga called To Love-Ru Darkness is when season 3 might be based on. If you did so happen to hear rumors that To Love-Ru Darkness manga series does not exist, do not listen to those. Instead, just search it up online for the scans or something. Anyway, season 3 might be based on this manga but there's a chance that it would not because the manga series actually has a "dark" storyline. There are some uncensored parts and dark plots and twists or turns in the manga. But, fortunately; Ru lights things up in this manga and bypasses those dark plots somehow. Also and of course; that there are some new characters introduced.
This is old but if you didn't hear; Anime New Network reported that a online Japanese newspaper called Mantan Web mentioned that "Saki Hasemi and Kentaro Yabuki's To Love-Ru -Trouble- Darkness manga spinoff has an anime adaptation planned". But, it got removed and later; the official Twitter account for To Love-Ru anime said that this is a "mistake". This was reported on Feb. 27-28, 2011. But, there are still high hopes and rumors that To Love-Ru Season 3 will come out eventually. We will have to keep our fingers crossed.
If you already had seen both seasons of the anime and the main manga, once again; look for the To-Love Ru Darkness manga series in case that you did not yet. It's a must read if you're a fan of this series.
Source: Anime News Network