Feel your pain on that one. Wood grain is not just a pretty pattern. It shows where the wood is strongest and weakest. I ruined a nice piece of oak once by cutting against the grain. The split ran all the way through and made it useless. Now I always check the grain before I make any cuts.
Yeah it's like we keep learning the same lesson in different areas. Like how you shouldn't force stuff that clearly isn't meant to go a certain way (ask me about my last IKEA build). The grain always tells you what's up if you just look.