Beauty is the eyes of the beholder. [简明汉英词典] Beauty lies in the lover's eyes. 牛津字典中却给出的短语是“in the eyes of sb /in sb''s eyes "Although traditionally 情人眼里出西施 is translated as "beauty is in the eyes of the beholder", the two are not equivalent.

Valentine's eyes to Xi Shi

Beauty is the eyes of the beholder

There's a beauty/Venus in the lover's eyes.