The Cow - 2:235
There is no sin on you for informing them of your proposal of marriage, or for keeping this intention within you. Allah knows what you think about them. Do not meet them in secret except for the purpose of talking to them in a proper and virtuous manner. And do not attempt to marry them before their waiting period has expired. Know that Allah knows what is in you, so beware of Him. And know that Allah is Forgiving, Compassionate.
If you marry women and divorce them without sexual intercourse:
The Coalition/33:49
O you who believe, if you divorce believing women after you have married them and have not had sexual intercourse with them, they do not owe you a waiting period (before they marry another).
The Cow/2:236
It is permissible for you to divorce women before you have touched them or before they have paid their mahr. In that case, pay them. The rich should compensate them according to their means, and the poor should compensate them according to their means. This is the duty of the righteous.
The Cow/2:237
If you have divorced them after you have paid the bride price, but before you have touched them, you should give them half of the promised bride price. Unless the wife renounces her right or the husband wants to give the full amount. It is more virtuous for you to give it up. Remember the friendship between you. Allah is All-Seeing of what you do.