So with forest spirits of her kind, the usual was to find a human to seduce to tide them over for a few days. But:
1) the modern world doesn’t allow for that as much
2) Tzuyu isn’t really up for that anymore now that she has people she cares about
So she’ll handle things herself until someone’s able to visit her.
Chaeyoung tends to stay with her for a week or two at a time. During her heat they’ll stay longer if need be, and Momo will come over more often too.
And if either of them can’t help her and she’s really really needy, she’ll beg Dahyun to help her (when she’s around), but it’s a last resort out of desperation