Octave. You have to read it it's one if the most nature and well developed romances I've read. 1l1g3h

Ugh.. I hate NTR..unless the guy somehow gets revenge for the girl's betrayal. Some of these..are they really netorare? Competing for a girl's heart(like Yume de Aetera, for example) doesn't really seem to be so to me. Now..having the heroine girl stolen from the protagonist(like Kimi no Iru Machi or Gelatine Boy)..that's NTR.

If all it takes to be considered NTR is have the main character competing for the girl's heart...then that would include every manga that has a love rival. That's not NTR.

Hmm.. It's a Shoujo..but could Vampire Knight count?

Actually competing for girl can count as NTR if it is showned from one of the guys positions. Because then readers usually side themselves with the hero and rage about seeing the other girl going out (even if still not choosing but flirting can be just as painful) and experience rage/jealousy which is the main point of NTR.

Wolf Guy has a strong type C NTR.

And Vampire Knights... technically it could be but in truth we are never showed one guy as a protoganist so you can choose either of the two. If you take Kaname side then it isnt much of NTR, on the other hand from Zoro's POV its as hard NTR as it can get.

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Quote from alexdhamp

Ugh.. I hate NTR..unless the guy somehow gets revenge for the girl's betrayal.

The only one I can think of where that happens is Voyeur.

Nozoki Ana (in volume 5 I think)

Chisa x Pon (stopped being scanlated but luckily the raws are everywhere)

Ano ko to Issho (releases have started to pick back up)

Suki desu Suzuki-kun!! (only in recent raws)

Heroine Shikkaku

3D Material

Candy Life (more netori than netorare)

Girlfriend (has a LOT of NTR)

Bunbetsu to Takan (unbearably stupid imo, but it has what you're looking for)

LOOK AT MY WITTY SIG!!11!!!!11

Not allowing hentai makes me question what you really want.

I'm reading freezing, and the author has decided to demean his main character by devoting arouns 8 chapters (of a monthly release manga so like about a tenth of the series to NTR pairing)

people have commented the author does it constantly I think demeaning him main character females but I dunno.