The following enquiry was made to the maraji`:
Does a man shaking hands with his wife or touching her upon entering the house nullify his wudu’? May Allah reward you with good for your answer.
The marja,` Imam `Abdur-Rahman ash-Shami, may Allah preserve him, said the following:
According to the school of Imam Ahmad ibn Hanbal, then wudu’ is nullified by a man touching a woman or the opposite with desire; but if there is no desire present, then the wudu’ remains established.
As for the scholars of the school of Imam ash-Shafi`ii, then the wudu’ in such a case would be nullified with or without desire.
Taken from the website of the maraji`