"She decided to leave her job."
Translation:Hun besluttede sig for at forlade sit job.
Apparently beslutte can be reflexive or not in usage. It follows that this English sentence is ambiguous. Either she made up her mind (reflexive usage) or she put into force her decision (NOT reflexive). That said, it is not wrong to leave out the sig, since there is no indication as to which meaning of decided is meant here. Please allow for more than one correct answer!