Is it permissible to refuse a good Muslim for personal reasons?

He has contacted her several times saying that he wants to propose marriage, but she does not know anything about him

Chatting Before Marriage in Islam

She has received a marriage proposal from a person who has some shortcomings which she is trying to deal with and discuss

a fiance to be alone with his fiancee

He is attracted to a woman who is engaged to someone else

It is not permissible for a fiancé to be alone with his fiancée

Ruling on engaged couple touching one another etc.

Seeing a number of women for the purpose of marriage

He is afraid that he will offend his friend if he proposes to his sister