This question already has an answer here:
I am a college student and I am currently doing a co-op where I have the opportunity to return for another co-op term in the summer. There are things that are very good about the worl environment there as a co-op but some things are not great.
If I had another co-op/internship lined up for the summer (that I thought would be better ) I would not want to come back to this company but I do not currently so when asked if I am interested in coming back, I said yes.
I have been applying to other positions, so in this case would it be unethical or come across very badly if I accepted another position, then email my current employer to tell them I am no longer interested in coming back?
For more context: I have not signed anything for the summer, the goal of the program is to have students return multiple semester but you are officially hired new each term.
Additionally, the person organizing the coop program hinted a bit that there is a slight possibility that they wouldn't be able to take the co-ops back another term for corporate business reasons (although they said they intend to but that the uncertainty is part of working for a large company)
I have seen other questions about going back on a verbal offer however the context here is different: saying you are interested in returning for another coop term is a little different than accepting a new job offer