Your ex-girlfriend pays you a visit, you two have kept in contact since she broke up with you.
You have been feeling down lately and seeing her always cheers you up. She tries to pry out of you what's got you so upset. You can't keep secrets from you, so you spill. You tell her you've lost your confidence since you two split up. Your cock just hasn't been able to last like it used to. Your ex recalls you having issues like that towards the end of your relationship.
Maybe it was something she did...but how could she do that?
She admits that a few months into your relationship she...

Your ex-girlfriend pays you a visit, you two have kept in contact since she broke up with you.
You have been feeling down lately and seeing her always cheers you up. She tries to pry out of you what's got you so upset. You can't keep secrets from you, so you spill. You tell her you've lost your confidence since you two split up. Your cock just hasn't been able to last like it used to. Your ex recalls you having issues like that towards the end of your relationship.
Maybe it was something she did...but how could she do that?
She admits that a few months into your relationship she knew it wasn't going to last, and as an act of revenge for wasting her time on you, she decided to condition your cock, little by little, to make it only be able to last only a few seconds. Then she would dump you.
Poor loser, she really destroyed you.