1. Aunt/Nephew, Son watching mother cheating, Cheating-wife, Olderwoman-younger man - Pingpong (2006)  - https://www.imdb.com/title/tt0800159/

1080p with english subs - https://lustycinema.li/watch/pingpong

2. Cheating wife, Cheating boyfriend with girlfriend's mother - Hardkor Disko (2014) - https://www.imdb.com/title/tt3671676

1080p bluray with english subs - https://lustycinema.li/watch/hardkor-disko

Levottomat (2000) - https://www.imdb.com/title/tt0231971

Cheating wife/boyfriend/ Cuckold Husband

1080p - https://lustycinema.li/watch/levottomat

One of my fav movies, Andreaskorset (2004) - https://www.imdb.com/title/tt0383184/

Cheating wife/Cuckold Husband/Older man-Younger woman

720p , webrip version - https://lustycinema.li/watch/andreaskorset

1. Antares (2004) - https://www.imdb.com/title/tt0419449/
Cheating wife/ Explicit-sex/Nudity

720p HDTV version - https://lustycinema.li/watch/antares

2. Cidade Baixa (2005) - https://www.imdb.com/title/tt0456899/
Love Triangle / Interacial

1080p WEBRip - https://lustycinema.li/watch/cidade-baixa

Presença de anita (2001) - https://www.imdb.com/title/tt0287262/

Cheating husband / Older man - Younger woman / Cheating girlfriend / Interacial

Best version of this series currently , 1080p WEBRip from Globoplay - 

https://lustycinema.li/watch/presena-de-anita

Letzter Moment (2010) - https://www.imdb.com/title/tt1677573/

Cheating fiancee with mother's ex-boyfriend / Older man - Younger woman

https://lustycinema.li/watch/letzter-moment-1

Note - Best quality of the movie i could find, There's a version on youtube but it looks very weird. This version is better than that.
However this movie was once part of Arte catalog so it was available in HD but couldn't find any sources for that version as of now. I'll keep an eye on Arte's catalog in-case this movie comes back

Bunch of good movies in best quality available online , 

Ha-Shiva MeHodu (2002) (1080p WEBRip) - https://lustycinema.li/watch/ha-shiva-mehodu

Bastaard (2019) (1080p WEBRip) - https://lustycinema.li/watch/bastaard

Les Innocents aux mains sales (1975) (DVD Remux) - https://lustycinema.li/watch/les-innocents-aux-mains-sales

L'enfant de l'hiver (1989) (1080p Bluray) - https://lustycinema.li/watch/lenfant-de-lhiver

L'amour et les forêts (2023) (1080p Bluray) - https://lustycinema.li/watch/lamour-et-les-forts

1080p WEBRip version of La mujer del juez (1984) 

https://lustycinema.li/watch/la-mujer-del-juez

Tags - Cheating wife, Older woman - Younger man, Forced sex, Wife blackmail , IRL Married

Amor Estranho Amor (1982) - https://www.imdb.com/title/tt0083552/

1080p version-
https://lustycinema.li/watch/amor-estranho-amor

Mother-Son Incest,  Cheating girlfriend, Son watching mother having sex , Older woman-Younger woman

Brazilian queen Vera Fischer giving it all in this movie. She was married to director Perry Salles (1972-1987)

Addicted (2014) - https://www.imdb.com/title/tt2205401/

Cheating wife / Interacial

Uncut 1080p version - https://lustycinema.li/watch/addicted