Let's be honest, this GF is not ignoring OP because she is "trying to pass college." That isn't something that a high-interest woman does. People get busy -- but not talking and blocking him on Snapchat? Come on.
You seem to take issue with the advice specifically to go out and bang other women. I will agree with you to an extent that I, personally, am simply not ready for that kind of thing at the end of an LTR. However, it works for some, and it isn't "doom and gloom." Again, it is a tactic to get your brain to remember "hey, there are OTHER women out there besides my ex - she ISN'T the last/greatest woman in the world."
That sounds like very level advice.
@Jake_Gyllenhaal69 I also am against breaking promises if any exist. In what I suggested I specifically told is OP's choice, but simply to revalidate to only himself that he has such a choice.
It is more for his spirit than to save any relationship. he might be able to buy or beg or submit and keep her for longer but the quality of his life will be lacking. Most men do not feel good when they are forced into submission from a woman. I know it first hand.
The girl probably is not bad, but university is of higher priority to her, assuming that's all it is. That's fine, if OP wants to keep her long-term and be happy about it he needs to be ok inside about her priority. Clearly, he wants her to prioritize him over all else as most men want. The reason for the question.
It's not about getting her back it is about him being ok with how the world works, if she really chooses him that's ok as long as he wants her.
Any woman that has found "the one..." will simply drop her entire world to be with him and that is what most every man wants deep inside. This woman is not going to do that for him at this time. He needs to be ok with that, fastest way to break oneitis is another woman or to actually catch her cheating.
Following married red pill advice would strengthen his position if she is on the fence or even out of the yard. At the same time, it will also help him if this woman does not work out for him to filter any new ones.
Remember, deep deep down, women are attracted to greed, not generosity. just how it is.