Probably am, probably everyone else knew this except me but this is taken from the gov.uk website
"Adultery
Your husband or wife had sex with someone else of the opposite sex, and you can no longer bear to live with them.
It doesn’t count as adultery if they had sex with someone of the same sex. This includes if you’re in a same-sex marriage.
You can’t give adultery as a reason if you lived with your husband or wife for 6 months after you found out about it."
So, if you are a lesbian and your wife has sex with another lesbian then you cannot divorce her on grounds of adultery! It only counts if it is PIV sex!
I am sure, as I said, that this is just me late to the party but surely when the marriage laws where changed to allow same sex marriage then the divorce laws should have been updated at the same time? Interestingly, adultery is not grounds for ending a civil partnership, so perhaps the best thing would be to end it being grounds for divorce too in order to have parity across the board?