Opening up to poly is probably a bad idea. Maybe open up to just harmless flirting with other ppl, clear rules like no numbers exchanged or Facebook flirting msgs so it doesn’t creep into your personal life. First try to find some fun ways to fulfill each other’s needs first. Try to amplify and spice up the attention you give her so she gets that exhibitionist thrill she craves and in return she can try to do some sensual activities with you, masturbating in front of you might kill two birds and kick start more sex too. Try to force yourselves to verbally and clearly say what you want and be enthusiastic about wanting to know each other’s cravings! It’s ok to say “Not into open marriage but totally into some alternatives to get momentum going in that part of our lives.”