What is the ruling of Islam regarding fining the husband when he arbitrarily seeks divorce due to regretting his choice of wife and desiring to marry another, and is the husband sinful for doing so?

Fining the husband for divorce is impermissible, as it constitutes consuming people's wealth unjustly (akL amwāl an-nās bi-l-bāṭil), and divorce is the husband's right. The husband should be patient with his wife, even if he dislikes her, for there may be good in that. However, if he divorces her, there is no sin upon him, as divorce is permissible.