Temporary Mom

Arunrada decide to blackmail Pathiharn, the man she has just met, for 500K baht, because her sister needs money very badly. Aware of her trick, he gives her an offer to be the mother of his son whose mother, Pimrada, has gone missing for 5 years. While she's being a fake mother for Pathiharn's son, they develop romantic feelings for
each other. However, his wife who was missing, finally returns.
(Source: Thaidramatic_update; Edited by Soju at MDL)