Is it permissible for a young man to suck his female companion's breast?

If the woman is a non-mahram to her husband's friend, then she must wear a full hijab, and it is not permissible for him to touch her or be in seclusion with her, based on the Prophet's (peace be upon him) saying: "For one of you to be stabbed in the head with an iron needle is better for him than to touch a woman who is not permissible for him." And it is not permissible for her husband to enable his friend to commit this heinous act.

If the woman is a mahram to her husband's friend, it is still not permissible for him to expose her breast because it is 'awrah, and if it is done with the intention of pleasure, it is even more reprehensible.

Therefore, it is not permissible for the man to suckle from that woman's breast, whether she is a non-mahram or a mahram to him. And if he does suckle from her, it is not considered a valid suckling that establishes mahramiyyah.