Civil partnerships only came about because the UK refused to allow gay marriage - civil partnerships were the compromise. But then of course the law was changed and gay couples were allowed to get married. So everyone had the opportunity to either get married or have a civil partnership. Legally they are basically the same IIRC, with the same legal and financial protections.
I know two straight couples who had civil partnerships, and I’ll admit I rolled my eyes a bit at how badly they wanted to show they were different to everyone else