I can understand how you wish things were different. But please don’t wish you didn’t know the truth!
If he knows you know, and still love him, and want to see him, this could give him great comfort and strength to return to a clear conscience.
I’m not suggesting to have an overwhelming agenda to only want him to remain chaste, but that you love him anyway, and still hope him to be chaste.
Help him know you are a sincere friend during ANY period of his life, and you may be able to be a positive force in his desire to becoming chaste.
Just imagine the struggle he must face, if he is to be chaste, in his temptation!! And you must be the bigger person of you are to compel him towards chastity.
And possibly, he will find female companionship one day. But don’t count on that.