I need some recommendations of beta x alpha couple that doesn't contain rape. Thank you.

Only one I know is http://www.mangago.me/read-manga/tadaima_okaeri/

Second couple, though their part is still going. Super sweet all around.

http://www.mangago.me/read-manga/kashikomarimashita_destiny/
2nd couple, but they have bigger portion of the series, no rape between them

Not between them but I think it does reference it between one of them and some no name characters.