In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
1- The scholars have different opinions as to whether touching the penis invalidates wudu or not. The most correct view is that if touching the husband’s penis is done with desire, it invalidates wudu.
2- If a man shakes hands with his wife or kisses her, or she kisses him, that does not invalidate the wudu of either of them, even if it is done with desire, so long as nothing is emitted.
Answering your question, the Fatwa Center at Islam Q and A, states:
If a woman touches her husband’s penis with desire, it invalidates her wudu, but if it is without desire, then it does not invalidate it.
Imam Ulaysh said in Minah al-Jaleel Sharh Mukhtasar Khaleel (1/113):
“The ruling on touching the penis of another person depends on whether it was done deliberately or whether accompanied by desire.”
If we say that it does invalidate wudu, that is on condition that there is no barrier. This is the view of the majority.
So if a woman touches her husband’s penis with a barrier, her wudu is not invalidated, even if it is with desire, because of the report narrated by Abu Hurairah (may Allah be pleased with him), according to which the Prophet (peace be upon him) said: “If one of you touches his private parts, with no barrier in between, then let him do wudu.” (Narrated by Ash-Shaafa‘i in his Musnad, 1/12; classed as authentic by Al-Albaani in Saheeh al-Jaami)
If a man shakes hands with his wife or kisses her, or she kisses him, that does not invalidate the wudu of either of them, even if it is done with desire, so long as nothing is emitted.
That is because of the report narrated by Aishah (may Allah be pleased with her), according to which the Prophet (peace be upon him) kissed one of his wives, then went out to pray and did not do wudu. (At-Tirmidhi, An-Nasai, and Ibn Majah)
Sheikh Abd Al-Azeez ibn Baz (may Allah have mercy on him) said:
“The correct scholarly view is that it does not invalidate wudu at all. If man touches his wife or kisses her, it does not invalidate his wudu according to the most correct opinion, because the Messenger kissed one of his wives, then he prayed and did not do wudu. Also, the basic principle is that wudu and purity remain intact, and it is not permissible to say that it has been invalidated by something unless there is proof to that effect, with no counterproof. In this case, there is no proof to indicate that wudu is invalidated by touching one’s wife at all.” (Majmu al-Fatawa, 17:219)
Almighty Allah knows best.