Is it forbidden to speak online with a university colleague about academic matters, which sometimes goes beyond that framework to discuss personal issues, even though the mother is aware of it?

Satan tempts a Muslim to sin. While a conversation between a man and a woman may be permissible in origin, it can develop into expressions of love and an illicit relationship. Therefore, the relationship with the young man must be severed, and charitable work should be pursued through legitimate means. The mother's awareness of the conversations does not justify their continuation. Marriage is more beneficial for those who love each other, but if it is not possible, do not delay marriage while waiting for this young man, as he might leave you and marry someone else, and you will regret it.