Played the game in Japanese too. (I understand Japanese btw)
The red hair girl is MC's fiancé. The blond elf is his stepmother/guardian (essentially) who also "love's" MC. The pink priestess is sorta a love interest who is the mercenary "bull" character's lover then there is also the blond housewife alchemist. The blue haired "siren" is sorta love interest too. No scenes with Succubus boss or the catgirl.
The game has a pretty unique take on NTR. It mixes NTR and NTRS genres into some wild mashup. Basically the MC has a fetish for being a cuck BUT the Succubus boss who resurrected him, his fiancé and stepmom also has a fetish to MAKE people get NTR. She want's to see people being cucked, cause it is how she gains "energy" also the plot device of regaining her true form. MC is indebted to her and is into being cucked (sorta lol)
That's basic gist of it.