Is it obligatory for a girl who has hair on her breasts to inform every suitor of her condition, despite the potential embarrassment this may cause her and her family, or should she not get married at all? And is this considered a defect that prevents marriage?

This does not prevent one from thinking about marriage, as a happy marriage may occur with him, for Allah Almighty says: (And it may be that you dislike a thing which is good for you and that you like a thing which is bad for you). What is more conducive to a good relationship is frankness about everything a person believes that concealing it is deception, for the Prophet, peace and blessings be upon him, said: "Whoever deceives is not from me." And "Righteousness is that with which the soul feels tranquil, and sin is that which wavers in the breast and which you dislike for people to know about." It is not possible to determine whether this is a significant defect that must be disclosed or not, without knowing the level and manner of hair growth.