Well, that is disappointing. The MC is a bit of a douche and it would be poetic Justice for his GF to get a baloney sandwich from another.I think it's the Mom that is "ntr" and I totally get it from the dev. People keep asking for incest and get upset when Mom gets cock from different men. Also the sister too.
It's pretty clear and confirmed Becky will not get any cock other than from MC.