Ah, the joy and frustration of running a marathon. I know it well. Yep, training hard to try and BQ at a marathon and then not making it just sucks. Been there, done that. Yes, you can still have a good time and most importantly want to get out and try it again. Any good news? If you manage to BQ in your next race, or the one after that, or in my case the one after that one well when you do it is something else! You will get your BQ race at some point. Once it happens all of those past marathons will suddenly becomes memories and stories you will always cherish. Good luck with your next race.