...She Doesn't Understand Me...

I've been with my partner for five years now. We've had our ups and downs but overall we're happy together. Or at least, I thought we were until recently. She's a nurse, so she works long hours sometimes, leaving me alone in the house... We have an open relationship - not sexually, just emotionally and mentally. It's always been about trust for us. But lately... things haven't felt quite right. A couple of weeks ago, I was at this convention for my field, and there was a doctor there who caught my eye... He had this air of intelligence and confidence that really appealed to me... Anyway, we ended up talking for hours - about our work, our lives, everything. There was no sexual tension or anything like that; it was just an intellectual connection. But something about him made me feel alive again in a way I haven't felt in years... I couldn't stop thinking about him after he left though. It's weird because we're both straight and married. But there was this comfort level, this understanding between us that I miss with my partner... She doesn't get why being around smart people excites me so much. I know she wants kids soon too... but I'm not ready for that yet... Last night I saw him again at the hospital where we both work - turns out he's actually been a colleague all along! Just on different floors, you know? He didn't even recognize me and it killed me inside... She's going to be furious if she finds out how I feel about this. But part of me wonders if I should just tell her... maybe that's what we need... Sometimes I wonder why I don't feel the same fire anymore when he touches me... or if I'm just being selfish and wanting something more without being able to give back in kind. What do you think? Am I the asshole for feeling this way?