That feeling when your crush said to you, “I love you”, and after you elatedly answered “Oh wow really? I love you, too!”, she/he continued, “Well, I mean as a friend…”.
はしごを外す (はしごをはずす, hashigo wo hazusu) is an idiomatic expression that literally means “take the ladder off”. Figuratively, it means the act of “betrayal”: to encourage someone to do something at first (putting a “ladder” for them) and then suddenly disagree with what they’re doing (take off the “ladder”). Here is an example:
Friend: Actually, I don’t like him. What do you think about him? [putting a “ladder”]
You: Yeah I really hate him, too. He is so self-centred and f*cking annoying!
Friend: Wow, I didn’t think that much! [taking the “ladder” off you]
Here, your friend puts a “ladder” that leads you into shit-talking, and suddenly takes off the “ladder” after (whether on purpose or not) eliciting your candid opinions. In this situation, you’d feel “はしごを外された (the ladder has been taken off)”, meaning you suddenly feel betrayed and abandoned by your friend.
In a more formal context, はしごを外す can also mean “to pull the rug out from under someone”, that is, to suddenly take support away from someone. For instance, if the government encourages researchers at university to work on particular topics by providing sufficient findings, and in a couple of years, stops the support because they no longer regard them as “essential”, that’s a typical act of はしごを外す (taking off the ladder).
[An example of when your ladder is taken off]
Your Crush: I love you! [putting a “ladder”]
You: Really? That’s so great!!!! I love you too since I met you for the first time!
Your Crush: Wait, what? I mean as a friend… [the “ladder” is taken off]
I was very happy because I was appointed as the project leader by my boss. However, the project was cancelled suddenly and now I feel “the ladder has been taken off”.
Synonym: 裏切る (うらぎる), betray
Synonym in English: pull the rug out from under someone, double-cross
Related Word: はしご (ladder), 外す (はずす, detach, take off, remove)