DD is in Y11 and has had a pretty tight friendship group for most of primary and high school. These days, as is to be expected, they are splintering a bit as people head in slightly different directions etc. but there has been one of this group that she has always been closest to, and we know the family well and have holidayed together etc. However, at the moment (and since maybe July), this particular friend has been in a bit of a frenzy about 'her future', and spends her time talking of nothing else but which 6th form/college she is going to go to (which changes every other week), how they're so much better than their school 6th form (not objectively true), her ambition for life, how she's pushing for really high grades etc. She's talking about 6th forms that are miles away with literally no transport or ways of getting there etc. so her wild ramblings aren't always particularly practical.
This wouldn't usually bother my DD that much, and she has gone along with the conversations nodding and showing interest etc. Both girls expect good grades at GCSE and are heading for A levels and probably university. What is upsetting DD a bit is this feeling that friend talks of little else, and it's tedious and at times there is a feeling that she is building herself up by putting others (including DD) down a bit. An example of this would be some extra 'stretch' English class that is happening in form time. Neither girl was selected to go to it, then friend's mum contacted school and asked for her to go, and now friend is going on about how it's going to help her get the grades she wants etc. and sort of implying that DD is going to miss out by not being in this stretch class (it's 15 mins a week so I'm not worried on that score). That's just a small example, but DD is just getting really fed up with so far the whole of Y11 being about friend going on about herself and her ambitions etc.
Left to her own devices, DD would be reasonably confident and happy in her choices, but the constant going on about it is making her feel low, and it feels like friend is making her feel small, even if she's unaware of it. She just wants to be able to focus on her own Y11 and not have this marr her experience, but also not be alone and friendless - she does have other friends but not ones she is as close and comfortable with. Reading back this sounds like a complete non-problem, but actually it's upsetting DD because she feels like her real friend has turned into somebody who is tedious, not supportive and not really all that nice.
I genuinely believe friend is not being a frenemy type or anything, I've known her her whole life and I think she's just hyped up into a bit of a frenzy about post-16 choices and it's all just coming out every minute of every day.
What I'm hoping for is advice on any ways DD could try to quietly shut it down? She won't want confrontation and won't want to fall out or lose friend completely. She just wants to not have this conversation be part of all day every day. I have talked to her a lot about focusing on her own plans and her own grades etc. and she has nothing to actually worry about on that score, she just doesn't want this to be a constant annoyance for the rest of the year.
Any advice on how to navigate this whilst protecting the friendship?