A sense of finality and irreversibility. It sounds like you might be referencing a situation where someone makes a serious commitment or decision, and it has significant consequences that can't be undone.

In some cases, this phrase could be related to:

1. **Marriage**: The idea is that once you're married, there's no "going back" in the sense of undoing the union.

2. **Business deals**: Signing a contract or making an agreement might mean locking yourself into a certain course of action that can't be easily reversed.

3. **Personal growth**: Reaching a point where you've made significant changes to your life, such as quitting a job or ending a relationship, and it's not possible to go back to the way things were before.

Which context do you think this phrase fits best? Or is there something else I'm missing?

Locked in