Rescuing someone who keeps diving back into the deep end turns you into a lifeguard with no breaks.

There is a difference between helping someone through a crisis and becoming the permanent solution to a recurring one. When the same rescue is needed repeatedly, your presence can remove the pressure that would otherwise force a change, and you hold a role you never applied for. None of that means the person is not struggling.

Work out what help actually changes something and what help only resets the clock. Offer the first kind and be honest about the limits of the second. You are allowed to rest, and resting does not make you the reason things got hard for them.