Hm, Thundarr, sounds like I have the female version of a few of yours...
"I should have worked less"
"I should have taken on less responsibility and let him experience his own problems until he solves them by himself"
"I should have paid more attention to him and realized he was slipping slowly into depression"
But also:
"I should have just let him rant about his work every evening, just repeating that he is doing fine and always will and that I love him anyway"
(which I also always believed), and not continue to brainstorm on what he could do to fix his 'problems' that aparently according to him now were none, besides that of course he never ranted (he did, I have witnesses, he has a reputation of being a big ranter - though he got me so brainwashed in the beginning I really started to doubt)
"I should not have left him to work in another county, I should not have let him go on "guys drinking nights " (turned out they weren't...)" maybe insisted to go with him? No idea what, always thought guys needed space (as I do so that was fine with me).
In fact I should have been more controlling, suspicious, less trusting.... don't know what. Still surprised about that one as I am now blamed for being controlling for anything I do. Wonder how I could have been less controling and less giving space than I was...
"I should have bought more sexy underware (and loads of other things, gone more traveling, restaurants, a newer car, etcetc)" instead of saving for 'his' house
Anyway, too late for now, or too early if ever...