Ejaculate During Foreplay?

I’ve been experiencing ED for the past few months. I’m 65, married over 40 years and have never had this issue for such a prolonged period. However, I also use viagra.

My issue is that after performing oral sex on my wife, to climax, whatever erection I have is gone. She then performs oral on me. I never get quite hard enough to penetrate her, and climax after 10 minutes or so during oral?

Is this common? Is it something that happens to others?