Get her brain thinking about sex before you even hit the bedroom. Most guys don't initiate foreplay until a woman is lying on the bed and they spend a few minutes playing with her breasts or teasing her, but that's about it. They seem to think that if she's wet, then she's ready. This is false.
That's correct. Foreplay for many women begins during dinner. I can touch my date's hand lightly, give her a wink, or stroke the inside of her arm gently. Many women like that. But every 10 minutes I do something like that. Or I might get up to use the bathroom during dinner, and whisper something dirty and brief in her ear, like "I can't wait to take you home with me."
My date the other night was so sensitive, simply me stroking her arm made her speechless. (That's not like typical women, but everyone is different.)
So you already covered stress, BC, and trying new things. This sudden onset makes me think of a hormone issue. For that see your gynecologist. I personally have experience with sudden drops in male hormones. It was bizarre and scary at the same time it could happen so fast.
I have a long time interest in psychology, specializing in relationship dynamics for 30 years.
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