why doesn't Wickham have warm feelings for Darcy ?

First of all....... Darcy isn't a her; he is Mr. Darcy.

Second, Mr. Wickham isn't fond of Mr Darcy because when Mr Darcy's father died...... Darcy threw him out. Mr Wickham tells Lizzy that Darcy's father was really fond of him and wanted to financially help him joint he ministry. Because Darcy threw him out, the ministry was out of the question, so he joined the military instead.