Responses
The Royal Family of Aristine is either Blonde with Green Eyes or Silver Hair with Purple eyes. Since she came in that place through Mirror/water(novel) it's the opposite effect like the mirror. Because the opposite of Silver Hair with Purple eyes are Blonde Hair with Green. She looks like her sister in this.

I wonder what’s the cause behind the FL’s change of appearance during this encounter with ML? From the spoilers I read ages ago, it’s never explained why she had blond hair and green eyes during this exact moment. Besides, I think it’s a poor attempt at creating a misunderstanding/hurdle between the two. Tarkan is allowed to have a first love but I think it’s been exaggerated to the point where he clearly understands his feelings for his wife but still hesitates to let go of finding his first love? The hesitation and cling to the past only shows his shakey resolve for FL.