It is my understandin that CO contaminated air would not be too much of a problem at depth because the partial pressure of oxyen, over-rides it. The problem is more on ascent when the oxygen pressure drops...so if the air tasted ok and nobody else had a problem, this is not likely.
If the diver was not over exerted and suffering from CO2 issues, then the simple answer is that the narcosis got to him, it initiated a panic attack and he exited the situation ASAP with no regard for his wife/buddy.
Freaked and Bolted...
Upsettingly, I am in agreement with DD
CO contamination is NOT a frequent problem at major dive shops....it is a rare event...while Narcosis and buildup of CO2 in the blood can be quite common in people diving to 100 or 120, or deeper. For a new diver, "trying" to control their breathing, slightly nervous and uncomfortable, this is indicative of a higher heart rate, and the "controlled breathing" will lead to CO2 buildup. This buildup will make narcosis happen much sooner, and be far more severe.
George Irvine, Bill Mee and I did hundreds of deep air dives in the early to mid nineties, till George came up with a way for us to switch to trimix. Only air was available in those early days... I will not say that anyone can master narcosis..... and management of it, sounds good in a Hal Watts deep air course, but means little to nothing in the real world. Some people are not as effected by narcosis than others, just as some will have one drink at a bar and be blasted, and another could drink 6 shots with little visible effect. We happened to be fairly good at dealing with narc, naturally. Once we learned how helium DRASTICALLY changed the dive, and how much more there was to the experience, we stopped the deep air, cold turkey !
You can decide you want to get hammered in a nightclub, or a cocktail party....that is your choice. I suppose you could decide you want to get hammered/drunk on a deep air dive.... If you do, the experience will NOT be like the experience YOU COULD HAVE HAD if you had done this on trimix. Some of our deep reefs and wrecks in Palm Beach are UNBELIEVABLE...the things you can see blow away National Geographic specials,. Discover TV specials...this is an experience overload that you need EVERY OUNCE of your brain recording, and processing, and experiencing....You don't want to be so hammered that you remember seeing the wreck at 280 feet, and the big amberjack school that covered it like a dense cloudbank, but have no recollection of the dense marine life all over the wreck, you somehow did not see the 16 foot hamerhead shark that visited briefly, then swam on, and one of your buddies told you about the huge shool of tuna that was being balled up by 6 foot long cuberra snappers, and the feeding frenzy that ensued....
I think there needs to be a "Recreational Normoxic Trimaix class" that any competent diver can do, for 100 to 150 foot dives...a 21/35 mix. The training for this is minimal if the diver is already competent. The class does NOT need to be expensive.
The cost of the helium for the trimix willo seem high compared to Nitrox, but you end up with an INTENSE experience, where otherwise it is/was largely, WASTED.
