How do I conjugate "need to" なければ x ならない plus "unfortunately" しちゃう？


I'd like to say "I unfortunately had to return (because of COVID)". I wanted
to use "nakereba" plus "chau". Does （COVIDのせいで）帰らなければなちゃいませんでした work?




しまう is usually used with verbs that describe an action or a change of state.
It may be used with いる, which is stative, but that’s when you regret your
action, or no-action, that puts you in a certain state as a result.

`[V ない-stem]-なければならない` refers to a state (where you have to do something) and
doesn’t go well with しまう as it is.

One option is to add しまう to the verb.

> 帰っちゃわなければなりませんでした。（more formally 帰ってしまわなければなりませんでした。）

However, this doesn’t quite sound like the speaker regrets the situation. It
sounds to me more like the act of 帰る is complete in some sense.

Another option is to convert the state into a change of state by adding なる and
then add しまう to it.

> 帰らなければならなくなっちゃいました。（more formally 帰らなければならなくなってしまいました。）

This sounds like the speaker regrets the change that resulted in a situation
that forced them to go home.

However, 帰らなければなりませんでした already conveys a sense of regret because it sounds
like the speaker is describing the situation as something they have no control
over.

