Colors have an effect on moods.
In our culture, pink is so ingrained as a color of girlishness or femininity. For myself, I’m attracted to very feminine features, and depending on the girl, if pink is a good color for her, it can really intensify her feminine aspects… making her sexuality stand out more.
The Sunday as were all taking leave, and she was headed for the airport, I finally told her I was in love with her.
Bingo. From the SDMB Archives:
My WAG is that it was her scent not her clothing that tripped your triggers. 
Could be she is in her fertile time of the month too, pheromones and such, which also may have her select a more ‘sexual’ mode of dress subconsciously. So the color may not be the cause at all, but your attraction and her choice of clothes may be linked to her fertility cycle.