Praise be to Allah.
Can a husband see his wife's private parts?
It is permissible for a woman to see all of her husband’s body and for a man to see all of his wife’s body, with no need to go into details, because Allah says (interpretation of the meaning): “And those who guard their chastity (i.e., private parts, from illegal sexual acts), except from their wives or (the captives and slaves) that their right hands possess, - for then, they are free from blame; but whoever seeks beyond that, then those are the transgressors.” [al-Muminun 23:5-7] (Fatawa al-Mar’ah by Ibn ‘Uthaymin, 121)
Can husband and wife bathe together?
Al-Bukhari reported in his Sahih (no. 250) that ‘Aishah said: “The Prophet (peace and blessings of Allah be upon him) and I used to bathe from one vessel.”
Al-Hafiz said in al-Fath: “Al-Dawudi interpreted this to mean that it is permissible for a man to look at his wife’s ‘awrah and vice-versa. This is supported by the report narrated by Ibn Hibban via Sulayman ibn Musa, who was asked about a man looking at his wife’s private parts. He said: ‘I asked ‘Aishah, and she referred to this hadith.’ This is evidence in this matter. And Allah knows best.”
I say: as for the words that some people attribute to the Prophet (peace and blessings of Allah be upon him), that it is makruh (disliked) for a man to look at his wife’s private parts, this is not sahih. This includes the reports narrated from Ibn 'Abbas and Abu Hurayrah according to which the Prophet (peace and blessings of Allah be upon him) said, “When any one of you has intercourse with his wife , let him not look at her private parts, because this causes blindness, and let him not speak, because this causes muteness.” Ibn al-Jawzi said: “(This is) mawdu’ (fabricated).” (See al-Mawdu’at by Ibn al-Jawzi, 2/271-272).
And Allah knows best.