A few concerns to be considered:
Both the breast augmentation and the BBL operations are operations, needing anaesthesia. Despite being a layman in such matters I can’t imagine they can both be done at the same time. So after the first procedure is done and she’s home recuperating, there’ll be post-op care required, who will perform that? Changing dressings etc can’t be appealing if not medically inclined.
Then, off back to hospital to perform the next procedure. After being sent home to recuperate, again who will attend to all the post-op care? Guessing a butt lift requires a load more dressings to be changed and wounds checked - bathing, laying on the front a lot, can’t do too much until the all clear from the Drs.
Cost for the procedures possibly do not include post-op care, dressings, trips back to the hospital for checkups etc etc. Time off work needs to be factored in for either of you.
And speaking of cost, if you are expected to pay for the whole shemozzle, perhaps the floodgates of requests will open and you’ll be asked to fund all manner of things. Other posters have mentioned the lips, the eyelashes, these are some of the things that are fashionable now. In 5 years time there’ll be new things for people to covet and feel these new things are what they are lacking. No one knows when this BBL fashion will end and when it does, she will want to have her butt deflated. At more cost.
If she is funding it all herself, no problem - her life, her body, her decision.
The biggest concern is surrounding her self esteem. If she is driven to these current ideals of beauty is because she doesn’t accept herself, there’s a reason for that. Does she feel loved and cherished for who she is and how she looks now? There’s a possibility she isn’t receiving the reassurance she clearly needs. People always compare themselves to others and often find themselves wanting in some way. Perhaps she needs reminding and reassured as to why you love her and that you are together. How will she view herself in years to come when the inevitable happens and she gets into middle age and older? Reassurance is key. The beauty industry is massive and merrily creates ways to make people feel inadequate within their appearance but luckily offering cures.
If it’s not a self esteem issue driving this, please reconsider funding any of it.