Kami nomi zo Shiru Sekai (The World God Only Knows)

Information:

MAL: View Kami nomi zo Shiru Sekai @ My Anime List
Genres: Comedy, Harem, Romance, Shounen, Supernatural
Episodes: 13 (40 Episodes - Full Series)
Premiered: Fall 2010
Rating: PG-13 - Teens 13 or older
Romance amount: High
Romance quality: High
Drama: Moderate
Fanservice amount: Low
Harem: Yes (Similar to Omnibus Format)

General:

The Couple(s):

Happy Ending:

Season 1: No
Season 3: Yes

Conclusive Ending:

No (Cliffhanger, No definite ending. Manga have it)

Conflict:

Love Triangle:

Season 1: No
Season 3: Yes

Love Rival:

Season 1: No
Season 3: Yes

Cheating:

Season 1: No
Season 3: Kinda

Romance:

Kiss:

Yes (For Plot Reasons)

Do they admit their feelings?

Anime: Yes (For plot reasons)
Manga: Yes (MC Confesses)

Do they end up as a couple?

Anime: Yes (For plot reasons)
Manga: Yes (MC Ended up with 1 of the girls)

Romantic closure:

Season 1: No
Season 3: Yes (In my opinion)
Manga: Yes

Important Notes:

WATCH ORDER
1. Kami nomi zo Shiru Sekai Season 1
2. Kami nomi zo Shiru Sekai Season 2
(Optional) But I highly suggest to go watch it
- Kami nomi zo Shiru Sekai: 4-nin to Idol
3. Kami nomi zo Shiru Sekai: Tenri-hen
4. Kami nomi zo Shiru Sekai: Megami-hen Season 3

The anime ended up at Chapter 189 of the manga