Is it permissible to leave a religious suitor if the fiancée does not feel happy or accepting towards him, and would she be sinful for that?

The Sharia encourages marrying a woman to a man whose religion and character are pleasing, as the Prophet, peace and blessings be upon him, said: "If someone whose religion and character you approve of comes to you seeking marriage, then marry him. If you do not do so, there will be tribulation on earth and widespread corruption." It also granted the woman the right not to marry someone she does not desire, as he, peace and blessings be upon him, said: "A previously married woman shall not be married until her command is sought, and a virgin shall not be married until her permission is sought." Accordingly, if you do not desire the suitor, there is no harm in refusing him before the marriage contract.