Dating my crush didn't work out because I couldn't remember their birthdate.



Get it? It's a joke that uses a pun based on the common expectation with "dating", being to engage in a romantic relationship with someone, then turns it around by instead using the definition of "deciding what time period they are from" by indicating you cannot remember the year they were born.

Which is a double-joke, because romantic pursuits often also do not work out if you cannot remember an important date such as your partner's birthday.



Thank you, thank you, I'll be here all day.