Need some advice for dudes performance

So my f buddy is having some troubles (some back ground honestly I think he may have FASD because he shows all the signs) so when we get going with foreplay then he gets hard then he looses it and so forth he said “don’t worry it just happens all the time” and last night I was kinda just watching him and it seems like he is so overwhelmed he would look at my whole body then start touching one part and quickly switch to another part and so forth... I sort of get this feeling he is overwhelmed or unsure what exactly to do and then it’s like he starts getting mad at himself because he wants to but he just cant stay hard. I wanted to stop him and be like listen. I’ll walk you through this its no big deal or big rush just breathe man but I also don’t want to seem like a jerk you know? Anyone have suggestions how I could bring this up and just ask him about it and ask what he needs in order to not feel rushed or overwhelmed?