Is it permissible to marry a man who is dissatisfied with his wife and wishes to marry to avoid falling into sin, knowing that there are fears of hurting his wife's feelings or divorcing her?

It is permissible for you to marry the man you spoke with, and this is not considered an offense to his first wife, because Islamic law has permitted polygyny. However, you must repent from engaging in extensive conversations with non-mahram men. As for him, he must fear Allah and fortify himself by marrying, or by fasting and increasing in supplication if marriage is not possible for him.