About 5 yrs ago my husband was diagnosed with aml 4, he take many meds, can that cause e.D.?

Yes. This is not uncommon at all.Please have him discuss with his dr. As some of the ED maybe because of worry about his disease or your well-being.This can be addressed helpfully.
Chemo and ED. If he is on chemo for leukemia then ED can occur, but that may be the least of the real concerns.