Python random - list index out of range

I am trying to make a program that reads words from a txt file and use them to create a word quiz where you choose the synonym of a given word from 5 options - the correct answer and 4 other random words.

The text file looks something like this:

alleviate,release,slacken
clique,sect,faction,clan
denigrate,minimize,belittle,derogate
...

Here is the code:

import random

b = input('Press enter to start, enter !END to end.')

with open('vocab.txt', 'r') as file:
    v = file.readlines()
    while b != '!END':
        group = random.choice(v)
        v.remove(group)
        group = group.split(',')
        
        word = random.choice(group)
        group.remove(word)
        correct = random.choice(group).replace('\n', '')

        choices = [correct]

        for i in range(4):
            group2 = random.choice(v)
            v.remove(group2)
            group2 = group2.split(',')
            ans = random.choice(group2).replace('\n', '')
            choices.append(ans)
            
        random.shuffle(choices)
        print(word.strip() + ':\n', choices)
        b = input('Which is the synonym?(1~5)')
        if b == '!END':
            continue
        a = int(b)
        
        while a-1 != choices.index(correct):
            b = input('incorrect, try again!')
            if b == '!END':
                continue
            a = int(b)
        print('correct!')

output:

Press enter to start, enter !END to end.
trifling:
 ['altercation', 'ravenous', 'neophyte', 'clique', 'paltry']
Which is the synonym?(1~5)5
correct!
escape:
 ['evade', 'churlish', 'expert', 'satisfied', 'worried']
Which is the synonym?(1~5)1
correct!
progeny:
 ['admit', 'alleviate', 'descendant', 'denigrate', 'dull']
Which is the synonym?(1~5)3
correct!
secondary:
 ['parallel', 'introduce', 'obeying', 'sympathize', 'regulate']
Which is the synonym?(1~5)1
correct!
poverty:
 ['impoverishment', 'impel', 'examine', 'pugilist', 'pilfer']
Which is the synonym?(1~5)1
correct!

But for some reason the process only repeats five times before it throws the error:

Traceback (most recent call last):
  File "FILE_LOCATION", line 19, in <module>
    group2 = random.choice(v)
  File "FILE_LOCATION", line 378, in choice
    return seq[self._randbelow(len(seq))]
IndexError: list index out of range

I think this might be because the list of words was becoming shorter and shorter, I didn't want any repetition so I removed a word from the list if it has been used before. But the number of remaining words were enough to chose 5 words randomly from after looping the process 5 times. Is there a way to solve this? Any help is greatly appreciated! :)