It's not about male friends distancing themselves though, it's about couples distancing themselves. It may or may not be a conscious decision by one or both parties.
It's about finding yourself no longer part of a couple and discovering that you no longer belong.
It's about seeing Facebook posts where your "group" have gone out and had a whale of a time - something you may have wanted to join in with but no-one mentioned it because they thought you'd feel awkward, which you might well have done and declined if asked - it's the asking that's important.
It's about suddenly feeling relegated into an unfamiliar box where you can be safely kept to minimise any unpleasant fallout.
It's about feeling like an object of pity, rather than a person.
It's about feeling as though your loss makes you of less value by 50%.
Again, whether this is rational or not, it's what can happen, and is being reported here.
It's a messy, hideous place to be, and it takes time to level out. The modern world doesn't allow for that time unfortunately.