I'm not excited about having sex with my wife anymore

I love my wife to death. We've been married for 10 years and have 4 year old triplets. I'm just not that excited about having sex with her anymore. She's a great mother and wife, the perfect woman really. We were each others first, and I always thought there would be a lack of excitement after we got married, but it's even worse now. I've never been cheated on, so I don't feel like that's the root of it. <br><br>I've been fantasizing about other women, almost obsessively. I will find myself lurking through tinder or trying to make connections with women at social events we go to. I just feel this overwhelming urge to be with other women. I'm not acting on it, but it's taking a toll on my mental health.<br><br>I've never been good at talking to women, so even finding a way to express this to my wife is just completely out of my wheelhouse. How or why would she ever agree to open marriage? She's just the perfect everything, so how do I express something like this? I would never leave her and I don't want her to leave me.