Is it permissible to divorce a wife whom the husband discovered had been in relationships with two colleagues through messages and conversations, and who used to stand with young men explaining knowledge to them, and he discovered that she loved one of her colleagues, spoke to him on the phone, and sat with him at the university, and she used to reject suitors before accepting him, and he cannot live with her, nor does he trust her, and there are no children between them?

Divorce is permissible, especially if there is a reason for it, but if there is no reason, it is disliked (makrooh).

Our advice is to consider your wife's current state and ward off intrusive thoughts by remembering Allah. Everyone makes mistakes, and the best of those who make mistakes are those who repent.

If your wife regrets and repents, then keep her and live with her honorably. If living together becomes difficult and you fear the marriage will not last, then divorce before having children may be easier and have less impact. Allah may enrich each of you from His bounty.