येन for what reason, बाला the young lady, तपस्विनी unfortunate, सुकुमारी delicate lady, सती chaste lady, मैथिली Sita, दुःखम् suffering, न हि (वि)जानाति does not know, for that reason, भर्तुः husband's, शय्या bed, सुखा comfortable, मन्ये I think.

Hapless Sita is young and delicate. Being a chaste lady, she, even in these (adverse) circumstances, does not feel the brunt. Hence, maybe she thinks her husbands' (hard) bed comfortable to her.