I'm just throwing out some random thoughts...
You're attracted to Laura, you don't mention (unless I missed something) that Laura and Greg have an open relationship in a sexual way? Even if do are there's a lot of steps between that and anything else.
You may be latching onto Laura's empathy, and desirability, and her being flattered that you want her, to bridge the gap you feel with your wife right now. If what you want is to see about dating Laura, and your wife doesn't want to date Greg... maybe you should start the discussion from there, and figure out what your possibilities are.
Basically I'm getting the impression you may be courting trouble because you are really upset your wife won't act patient and be more considerate, which is understandable but I think you may be on the verge of deciding it is easier to make rash decisions that may benefit you instantly instead of making sure you and your wife hash out her desire to make decisions that benefit her vs what benefits both of you, and to decide if your relationship still makes sense long term.
Happiness will never come to those who fail to appreciate what they already have.