pipenv is unable to find the right package version using pytorch index
I'm confused by how pipenv resolves the available package versions. I specified the index and I clearly see version 0.8.1 in the list on their download site

This is my pipenv version. I'm running on Mac OSX and installed pipenv through brew.
~ pipenv --version
pipenv, version 2021.5.29

Pipfile
[[source]]
url = &quot;https://pypi.org/simple&quot;
verify_ssl = true
name = &quot;pypi&quot;

[[source]]
name = &quot;pytorch&quot;
url = &quot;https://download.pytorch.org/whl/torch_stable.html&quot;
verify_ssl = false

[packages]
...
torch = {index=&quot;pytorch&quot;, version=&quot;==1.7.1&quot;}
torchtext = {index=&quot;pytorch&quot;, version=&quot;==0.8.1&quot;}
...

[dev-packages]

[requires]
python_version = &quot;3.7&quot;

The error when I run pipenv install:
Pipfile.lock not found, creating...
Locking [dev-packages] dependencies...
Locking [packages] dependencies...
Building requirements...
Resolving dependencies...
✘ Locking Failed! 
CRITICAL:pipenv.patched.notpip._internal.index.package_finder:Could not find a version that satisfies the requirement torchtext==0.8.1 (from -r /var/folders/0q/10lqt8nn6_l87q71lx_d233r0000gn/T/pipenv2ix9if8erequirements/pipenv-qm980cdf-constraints.txt (line 7)) (from versions: 0.1.1, 0.2.0, 0.2.1, 0.2.3, 0.3.1, 0.4.0, 0.5.0, 0.6.0)
[ResolutionFailure]:   File &quot;/usr/local/Cellar/pipenv/2021.5.29/libexec/lib/python3.9/site-packages/pipenv/resolver.py&quot;, line 741, in _main
...

The error tells me it can't find 0.8.1 and that I can only choose from a super limited set. Why is this? What can I do to fix this?

You are using the wrong version of Python. It's really that simple.
Read very carefully in the list of library versions in that list:
Torchtext 0.8.1 exists for:

cp36m = CPython 3.6m
cp37m = CPython 3.7m
cp38 = CPython 3.8
cp39 = CPython 3.9

You are using: CPython 3.7.
CPython 3.7 (yours) and CPython 3.7m (theirs) is not the same thing.
The &quot;M&quot; stands for a special malloc version of Python which is faster. You can't install an &quot;M&quot; library on a non-&quot;M&quot; Python.
Upgrade to CPython 3.8 or 3.9. I recommend using Pipenv + Pyenv together, which makes it trivial to install different versions of CPython.
