What should I do if my partner routinely loses his erection?

If your partner routinely loses his erection, remember firstly that sexual responsiveness is a combination of hitting the gas (giving good stimulation through all sensory modalities, including emotion and imagination) and taking your foot off the brakes (removing threats of all kinds) So almost always erectile dysfunction is not about a failure of stimulation but about an overabundance of threats, often in the form of stress, anxiety, depression, or, in this case, a recent history of trauma.

Therefore the solution to ED, assuming it’s psychogenic and not straight-up physiological, is not about changing the stimulation.

Instead, confronting ED is about removing threats of all kinds.

This combination of realities -- that it’s not about stimulation and it is about threats -- tells us that the worst thing you can do is to take it personally or judge or blame or worry or sweat it in any way at all. If it’s problematic from your point of view, it becomes a source of anxiety, which is the opposite of arousal. I know you might feel like a failure or you might be inclined to take it personally. Don’t. Your attitude should be one of bright, optimistic curiosity about the things you can do sans erection.