On the face of it, this post is rather sad, but maybe I'm sentimental.
We are all different, and our bodies age in different rates and ways, but it does seem a bit young, in a loving relationship to stop, unless you absolutely have to..
The OP is concerned and is brave enough to raise the subject.
A trouble shared is a trouble halved is a good axiom.
If you don't talk about it, to each other, and to others who have travelled the same road, you will never find solution to the problem.
Others will have met the same or a similar problem and found at least a partial if not a complete solution, which they might share with you..
Years ago, when we had a problem, S i L said something which solved our problem, and stands us in good stead many years on. Consequently, we still enjoy each other's closeness, although older than the OP. Not as frequently, but we still enjoy being extremely close.
If he has had a problem, and as we age, virtually all men do, there are ways of coping, medicines, or rings.
Build up his confidence, and make sure that you say that you are still attracted.
For ladies, and for both, lubricants are almost essential.
In the context of loving and gentle relationship, it should be possible gradually to regain some of the passion of younger years. tell each other what you fantasize about
Very gently, by word and deed, increase each others confidence. You both need to gain confidence in your bodies and in each other. Compliment each other.
Dress and eventually, undress, to impress.
It may be that the ultimate will elude you, both, but find other ways to give, and receive, pleasure,
It is not called intimacy for nothing.
Work at it, gently, and hopefully you will reach a satisfactory conclusion.