You should point out to him that there are negative side effects in men from having low testosterone besides sex. This include anything from muscle and bone density loss, depression, insomnia, chronic fatigue, and a host of other issues.

If he knows he has low testosterone, he should really think about going onto replacement. And while it's not a perfect treatment, it can really help with many issues outside of sex and cuddling.

Read this [source from Harvard](https://www.health.harvard.edu/mens-health/is-testosterone-therapy-safe-take-a-breath-before-you-take-the-plunge) for more information so you can get educated and help him. It is better to face something when you have all the information so he can make better judgement of if replacement therapy is right for him.