Never last long enough!

A little back ground, i lost my virginity very young and had two more sexual partners before i ended up with my ex-boyfriend.my ex wasnt experienced he had only one partner before me so i got to teach him and learn with him for almost 5 year what we both wanted and needed during sex. He didnt have a big dick (maybe 5 inches, not much girth) but it was enough to make me feel full and satisfied. He lasted for hours at a time and always made me O multiple times during sex. We seperated two years ago and i started dating my fiance.

My fiance is the total opposite of my ex. He has a very large dick (9-10in and thick) largest ive ever had and sex is great, we have started to explore different kinks but no matter how often we have sex he never last more than maybe 20 minutes. I thought it was bc he hadnt been with anyone in a while but its been almost three years and it hasnt changed. So i never actually reach my O before he does. He always offers to keep going but then I have to deal with the disappointment of him going soft and more frusration for me. Is there anything I can do to help him last longer? So we can both be satisfied.