It's the most vanilla of NTR there is probably. (This is the latest, and probably final part of series with this female lead and the male lead. https://www.dmm.co.jp/dc/doujin/-/list/=/article=series/id=48900/limit=120/sort=date/ whole series here - always same female and male leads) This final part shouldn't be tagged NTR at all since she has broken up with old asshole BF and is now a couple with MC.
Basic rundown of the story from the beginning is Nanase is kinda dumb but loveable girl who wants to pay for concert tickets for her current boyfriend or something silly. So she offers a no kissing/no raw sex, paid dating with the MC(who has always liked her because duh it's hentai). Her boyfriend is never seen, but only mentioned throughout the series and all of Nanase's lady friends think he's cheating on her already anyways and he's very selfish/asshole-ish and only cares about himself during sex so Nanase has never seen sex as something that feels good or makes her happy that's why she doesn't think the paid dating is a big deal.
Over the course of the series male lead treats her how a lover should treat her and she begins to have feelings, blah blah blah, eventually no-kissing/no-raw rule is lifted, more feelings, blah blah blah. In the part before this one the boyfriend breaks up with her but she doesn't feel anything because he has been cheating, but she has a moment of introspection and realizes she has just been doing the same thing. Queue lovey moment with MC where she doesn't think she's worthy of being loved by MC and he says he has only had eyes for her and always will, blah blah, officially together now.
On to this final part. They are now a couple but (OH MY GOD DRAMA!!!!!) her father doesn't approve(mother does approve though) so she runs away from home and lives with MC at his family's house "training to become a bride" as it says in the description on fanza. Lovey dovey begging for impregnation sex happy end.