OK there are very few differences between Marriage and Civil Partnerships.
So clearly the woman who wears the trousers wants to f*** about without sadsack handbag getting all upset and divorcing her.
Civil partners cannot call themselves “married” for legal purposes.
Civil partnership certificates include the names of both parents of the parties. Marriage certificates include the names of only the fathers of the parties.
Adultery cannot be used as a reason to dissolve the Civil Partnership. In a marriage, if one party is unfaithful this is grounds for divorce. This isn’t the case in civil partnership dissolution. Adultery isn’t recognised in same-sex partners.
Yes, I'd be happy for our friends and family to celebrate our lifelong commitment to each other and have nothing in principle against spending heavily for them to do so, but that is not possible due to clinically mental family members who would very likely ruin it (as they have numerous other landmark events over the years).
Nevertheless, I wouldn't have a civil partnership for the precise reasons you identify, but it also remains true that they are not entirely without merit.