It's possible that he was involved...or not. My personal opinion is that he would be stupid (not naive as some are saying, there is a difference) to have a girlfriend who is experiencing a lot of life changing things (car accident, Leukemia, etc.) and still never even visit her once and not even attend her funeral.
Not visiting her seems more plausible if he was involved. If he was involved he could have done so for attention of some sort. Some people think any attention is good, others hope for one type and get another. I hope this is not one of those cases but I don't know him or all the particulars so it's hard to say for sure.
Anything is possible. It might have been a sick joke on him and if that was the case, the problem would be that he doesn't have good instincts to see that something was fishy much sooner and should stay away from relationships where the person always has an excuse not to see him.