Hi, I Got Married 36 Years Ago. My Age Is

Hi, i got married 36 years ago. my age is about 63 years.my sex life was very much ok. we intercourse once a week with good feelings. Suddenly few months ago i realized my Penis is not standing while foreplay.Now its not stand even 20 percent. seems no feelings in my Penis. i m worried about it that. Pls suggest me. and let me know is there is any issue. I am diabetes but no smoking, no alcoholism, no overweight,no hormone problems no Psychological issues include, no any Stress,no money issues, no relationship issues etc, yosuf