My Obsession

I have been dating an awesome woman for a while now. She's a great partner, and she is beautiful and funny, and we're into the same sorts of things. She's really thoughtful and considerate, and I do truly love her.... however, I have found my mind over flowing with thoughts of her daughter.
I would never act on these thoughts, and I have tried to dismiss them. It started a few months back, She's always been discretely flirty with me. She will walk through wherever I'm standing in the kitchen to bump into or rub against me. She gives me these eyes that make me think she knows what she's doing.
Yesterday, I get home from work and she comes in the kitchen to talk to her mom and I, and she's not wearing a bra under her shirt. Her mom turns around to wash something in the sink, and she looks directly at me, and runs her hand on her shirt so it pulls back, and I could see her nipples were hard and I couldn't help but look. She is beautiful, and her tits are fuckin perfect! She saw me looking and paused for a few seconds before she saw her mom turning back around so she let it go.
She gave me a sexy little smirk before turning back around and leaving the room. She knew exactly what she was doing! I have had a really hard time thinking about anything else since then. I was worried about saying something in my sleep last night because I dreamed about her all night.
I'm strong and I will not let anything happen, but I can't say that I don't love the attention.