In Pride and Prejudice, Elizabeth and Colonel Fitzwilliam have a very personal conversation while on a walk. Colonel Fitzwilliam is Darcy's cousin. He is Darcy's command.
While sharing a walk with Elizabeth, Fitzwilliam begins to talk of his position as a younger son and his lack of money. He adds that he will have to marry a woman with money since he does not possess wealth. When he talks in this personal way with Elizabeth, she is under the impression that he would marry her if she had money. He explains that he could not marry without some attention to money. When he says this, Elizabeth blushes, thinking that Colonel Fitzwilliam may be insinuating that he would like to marry her. Truly, Colonel Fitzwilliam does seem to be sharing his intimate thoughts with Elizabeth:
'Our habits of expense make us too dependant, and there are not many in my rank of life who can afford to marry without some attention to money.'
After Colonel Fitzwilliam shares this very personal information with Elizabeth, she turns red at the thought that he may be hinting that he would like to marry her:
'Is this,' thought Elizabeth, 'meant for me?' and she coloured at the idea; but, recovering herself, said in a lively tone, 'And pray, what is the usual price of an Earl's younger son? Unless the elder brother is very sickly, I suppose you would not ask above fifty thousand pounds.'
During this time, a gentleman would ask a marrying price from the father of the woman he wished to marry. Colonel Fitzwilliam indicates that he will have to ask a marrying price since he is not wealthy.
Since Colonel Fitzwilliam never comes out and directly asks Elizabeth to marry him, Elizabeth is only guessing that Colonel Fitzwilliam is hinting of marriage to her.
The fact that Elizabeth blushes at his intimate comments proves that Elizabeth thinks the Colonel Fitzwilliam is interested in marrying her. She thinks his comments about having to consider money as a stipulation for marriage are directed at her.
Without money, he realizes that the two of them could not make it financially. Since he is in no position to financially take care of Elizabeth, he realizes that it is not realistic to even think of marrying Elizabeth.
Whether or not Colonel Fitzwilliam was making an advance or suggesting a proposal to Elizabeth, she blushes when he speaks to her about marriage. She obviously thinks he is indirectly sharing his wishes to marry her if the financial situation were not a concern.
Truly, Colonel Fitzwilliam is a desirable man. He is very much a gentleman. He has many admirable qualities that any woman would desire in a man. No doubt, Elizabeth has some serious interests in a man like Colonel Fitzwilliam. Truly, he is a fine gentleman and any woman would consider his marriage proposal a compliment.
Ultimately, the reader is left with the impression that Elizabeth assumes Colonel Fitzwilliam is interested in marrying her.