I do understand your point but that's not exactly how the tag system here works.
NTR Tag:
There are a lot of different kind of NTR themes packed under this one NTR tag. Netori, Netorase, Netorare, Cuckolding etc.
And depending who you ask you could say there is already Netori in it. Other would say even Lisa is not your girlfriend but you can still invest time, emotions and all in her and then you see her having sex with her Boyfriend where MC is sad about it.. some people would call that NTR other would not because she is not your girlfriend.
You can have sex with your girlfriends Mom - is that Netori?
Honestly I am not sure about all that. Fact is - You see girls having sex with other guys and the closest Tag for that is NTR.
Other tags:
There is also a group sex tag. A double blowjob is not what I would count as group sex. So if I would be looking for group sex and I would be disappointed but I did not add that tag and I am not allowed to remove it.
Same goes for Sex toys. You basically see it in 1 or 2 images and it's not even used. Or the sleep sex tag. Yeah MC is waking up Ava with going down on her but I don't think it's enough to be tagged as sleep sex.
So as you can see.. the tag system here could need some improvements.

But like
Dessolos mentioned the Ava scenes will happen in a few updates and than this discussion will finally have an end.