Tell them.
I’ve had this problem with my DM for years. Most notably when, in the grip of severe postpartum mental health issues and ina relationship taking an increasingly violent tinge, she told me to leave my partner and move in with her “stay until the baby is older” she said. “Well help you. You don’t need to worry about moving out. You can stay as long as you need”.
I desperately wanted someone to look after me / tell me what to do, as I was drowning -
so I left my partner and my home in London for “safety”.
3 months later she asked me to leave, because her partner wasn’t pulling his weight in the house, and that, plus the fact that there was a baby in the house so the washer was on all the time was “getting her down”.
So I was 300 miles from my friends/support network, crippled with postpartum anxiety/depression, had an 11 month old I was breastfeeding, no money except mat allowance, no way to do my job as it was London based, no access to savings, no home or furniture (ex kept it all and wouldn’t give me it), and... suddenly homeless.
It took a while for our relationship to come back from that tbh. Particularly when said partner (who she later admitted was the problem, not me and the baby) left her for another woman and I had to pick up the pieces.
I say all of this because- I’ve managed to salvage my relationship with her by being brutally honest about what her reneging on promises has meant in terms of impact on my life. And that I would prefer she never promised anything, that promised and went back on it.
She got the message. She now helps out with childcare one day a week and NEVER cancels unless she’s ill.