Why not, I just find it weird that Jenna doesn't stay with her brother when they've been more or less together since childhood, whereas Emily and Jenna has not seen each other for 9 years. my point of view they hardly know each other.
I understand that Jenne is getting closer to Emily so that her brother has a harem but not that she stays with Emily in the Ada end.
but I agree with you. it is the least successful ending.
Jenna could go to MC with Elly, the only explanation I gave myself is that in that case Emily would be left completely alone, in one stroke she would lose her "husband" and her daughters, so I think they wanted to give her Jenna as a consolation, to make the aftermath of MC's actions less painful for Emily.
it may be that both Jenna and Emily, after feeling betrayed by MC, had formed their bond, but it's a guess to make the ending credible, we are not shown anything to that effect