People tend to look for one reason, a simple explantation for complex emotional/multi cause situations, everything from interpersonal relationships to suicide is viewed like that.....when in reality, these are incredibly complex and layered things.
Aaron Hernandez probably killed himself because of the shame, humiliation, depression of what his life had become, in addition to the guilt of at least his family, the honorable suicide to make sure his wife was compensated probably allowed him a way out, and likely other factors, such as substance abuse, anxiety. Something could have triggered him that DAY, or that week.
It wouldn't be just one thing.