There is one ground for dissolution of a civil partnership: the partnership has irretrievably broken down.
To establish irretrievable breakdown the court has to be satisfied on one of the four facts laid down in CPA 2004:
•the respondent has behaved in such a way that the petitioner cannot reasonably be expected to live with the respondent
•the parties have lived apart for a continuous period of at least two years and the respondent consents to a dissolution order being made
•the parties have lived apart for a continuous period of at least five years immediately preceding the making of the application
•the respondent has deserted the petitioner for a continuous period of at least two years immediately preceding the presentation of the petition
Note that adultery isn't mentioned. It is when a marriage is ended--£5 to the charity of your choice for the first correct reason why!