Is feeling repulsed by the shape of a particular girl's foot considered a legitimate reason not to marry her, and will the young man be held accountable for this refusal, especially given a feeling of guilt?

A Muslim man is not permitted to establish a relationship with a foreign woman, even with the intention of marriage, because that is a means to fall into indecency. One must repent to Allah from this forbidden relationship. There is no sin upon a man for not marrying a woman if there is something in her that repulses him, because the presence of repulsion may prevent the realization of affection and harmony between the spouses. For this reason, the Prophet, peace and blessings be upon him, commanded the suitor to look at the woman he intends to marry before marriage, due to what results from it of preserving one's chastity, lowering one's gaze, the continuity of companionship, and the achievement of affection.