このベルトのせいで腰回りが苦しいわ。

この: this, these
ベルト: belt, roosevelt, strap
の: to, of
せい: cause, fault, blame, right, true, correct
で: in, at, on, with, by, over, through
腰: waist, hip, hips, lower back, lumbar, loins
回り: around, circumference, border, surroundings, rotation, circulation, fringe, detour, efficacy
が: is, there, but, ga, will, however
苦しい: painful, difficult, bitter, severe, arduous, agonizing, torturous, hardship, laborious, strapped
わ: i, w, wa, peace, circle, harmony