Here are some examples:
Stress:
Can over time reduce testosterone levels
Can over time cause increases in Estiadol and Prolactin
Can cause bad dietary decisions with long term problems
Can create abnormal anxiety which has negative impact on erections
Can create performance anxiety
Can alter or destabilize blood pressure.
Can cause depression needing medications which to treat depression cause ED
Can cause elevated blood pressure needing medications that cause ED
Stress is in fact a "killer" and can kill more than the person, it can kill their ability to have a good time or enjoy anything. There are tons of ways that stress can kill sex drive.
As men return from foreign deployment to battle areas, one of the common ways that the military is made aware of PTSD is conversations with wives or significant others regarding sexual performance.