(Spoilers, a small discussion about Cole's belief)
Compared to Cole's acceptance that he might not deserve the trust from people around him, I think the harder belief for Cole is that he and his fathers had some misunderstandings of being loving parents. Thus, technically, they are not "the most loving parents a kid could ask for" as Cole believed.
I mean, if Cole always hold the belief his dads (especially Marrow) are perfect, even in terms of family education, then he might blame himself too much for his misbehavior.
(You know, when getting reproached from the outside, kids tend to blame themselves rather than question the way they were raised or the influence from family. Because denying their family would be more devastating psychologically for kids.)