What should I do regarding my suspicion of my wife's secret betrayal, even though I love her dearly and cannot bear to be away from her?

The suitor is a stranger to his fiancée as long as the marriage contract has not been formalized. Therefore, it is impermissible for him to be alone with her, touch her, or converse with her without need. Establishing a relationship before marriage is a transgression of Allah's boundaries and an act of indecency akin to zina (fornication/adultery). Marriage has conditions and pillars without which it is not valid. The obligation is to cut off this relationship and hasten to repentance by abandoning the sin, regretting it, and resolving not to return to it, alongside seeking concealment and increasing good deeds. The marriage of a fornicator to the one with whom he fornicated is not permissible unless both have repented.