I recommend the following for her to share with him:
1- The presence of such desires is not sinful. It’s acting on these desires that makes it sinful.
2- This is his trial in life. Let him accept this trial and do his best to cope with it. Aren’t there people born with disabilities and suffer an entire life? This is their trial and Allah will compensate them. This person’s trial is to avoid homosexual acts in this life. It is not easy, but it is possible.