This can be a really hard issue for guys to face up to / to talk about honestly. So much of masculine gender identity, self esteem etc is tied up in their sexual performance. It could be that the reasons simply aren't terribly transparent even to him...

> he comes when he is ready (or when it feels to good to wait any longer)

What would happen if he waited longer? Is he concerned / afraid that he would lose his erection? Is it that by then he already feels that he has 'passed the point of no return'?

> he could control his timing when he was younger and I was able to get there sooner than I can now.

Perhaps it would help to hold off penetration until you are closer? To engage in manual or oral stimulation so that it won't take as long for you to get there? And / or to have manual stimulation along with penetration?