All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
The proposal for marriage should not be considered as a binding marriage contract. In fact, as long as the marriage contract has not taken place, none of the two parties is obliged to fulfill any conditions towards the other one as their proposal is only a promise for marriage. The Lawmaker has not set any punishment for not fulfilling such a promise. But breaking one's promise without a sound reason is an immoral act and a quality of hypocrites. It is narrated in a sound Hadeeth that the Prophet said: “Whoever has the following four (characteristics) will be a pure hypocrite and whoever has one of the following four characteristics will have one characteristic of hypocrisy unless and until he gives it up: (1.) whenever he is entrusted, he betrays; (2.) whenever he speaks, he tells a lie; (3.) whenever he makes a covenant, he proves treacherous; (4.) whenever he quarrels, he behaves in a very imprudent, evil and insulting manner.” [Al-Bukhari]
The man is allowed to talk to the lady to whom he is engaged as long as his objective is a legal one, such as having an idea about her reasoning, her intellect and her intelligence as talking is less tempting than looking. Besides, the man is allowed to look at the woman to whom he is engaged in order to find out anything that urges him to marry her.
Jabir narrated that the Prophet said: “If one of you proposes to marry a woman and is able to look at her at what could drive him to marry her, then there is nothing wrong with him looking at her.” [Ahmad, Abu Daawood and Al-Haakem]
But he should know that this talking should not be repeated and it should not include any bad words.
Allah knows best.