Regex condition: letters except 'crfl' at the end of the word or string are deleted?

Question

I tried:

re.sub(r'[^crfl](?=(\.|\,|\s|\Z))', '', val, flags=re.I)

on string

car. cupid, fof bob lol. koc coc, cob 

but the result is:

car cupi fof bo lol koc coc co

I don't uderstand, why lookahead assertion deleted commas and dots.

The result I'm for is:

car. cupi, fof bo lol. koc coc, co

Answer 1

[^crfl.,](?=(\.|\,|\s|\Z))

just include ., in negation list.See demo.

https://regex101.com/r/yX8zV8/5

or simply

\w(?<![crlf])\b

See demo.

https://regex101.com/r/eB8xU8/1