It's natural you'd feel that way at first.

Literal

Not-unreasonable [feminine-わ], at-first [inside-のうちは], that-way feel thing [feminine-よね].

無理もない = 'not unreasonable' — 'understandable, natural.' The feminine sentence-final わ and the combination よね add a feminine-marked, sympathetic tone. ~のうちは ('while during X') marks a temporal phase. A soft, validating response to someone expressing discomfort.