I have no idea what this is all about but yes if you want some help from us you need to give us info and the above would not be what we are looking for.

2 board picture frame will look much better on the deck, the 3d board will look out of place.

I think the point your husband is trying to make is sometimes you need to just make a decision and NOT look anymore. Its difficult with the millions of beautiful photos on Houzz but until this project is over he may have a point. Good luck!

I'd pull a tape from one corner of the deck to the other and repeat in an "X" fashion to check the deck for square, especially with picture framing. Unless you think a tapered last board looks good.