It is indeed a fluffy, fanfic-y canon to start with, and the fandom follows suit! So I think you'd be hard-pressed to find a lot of unhappy endings or high angst.
You might be interested in this one I read recently, since it brings in a little more realism about homophobia in hockey and what it would actually be like to deal with that... Bitty & Jack still get to be just as happy, but this shows Kent's experience, which is tougher: https://archiveofourown.org/works/13222230 (Doesn't end tragically or anything! Just, we see Kent having to deal with some of the fallout in his own life, after Jack comes out.)
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You might be interested in this one I read recently, since it brings in a little more realism about homophobia in hockey and what it would actually be like to deal with that... Bitty & Jack still get to be just as happy, but this shows Kent's experience, which is tougher: https://archiveofourown.org/works/13222230 (Doesn't end tragically or anything! Just, we see Kent having to deal with some of the fallout in his own life, after Jack comes out.)