When you are faced with a production of Donizetti’s Roberto Devereux, it is good to keep in mind that yes, it is ridiculous. It is ridiculous on the grand scale – it has the distinction of being (I’m pretty sure) the only story based on the life of the Earl of Essex that includes his execution but does its best to avoid talking much about the abortive rebellion he led in early 1601 that according to most non-Donizetti’s-librettist schools of historical scholarship was the primary reason he was executed. Also it leaves out the part where he tried to shift part of the blame for the rising to his sister Penelope (I am not making this up), which I suspect gives you a sense of why Donizetti’s librettist decided to leave this and many other things out of the libretto.
It is also ridiculous on the small scale – the ending has Elizabeth basically drop dead after she realizes she was wrong to execute Essex. Given that in this version, she has him executed basically because she’s mad at him for loving another woman, I suppose maybe she was embarrassed. You know how sometimes you’ve momentarily wanted to drop dead, when you’ve done something really stupid and everyone in the room knows? Well it may be that if you’re an anointed monarch, you can actually do this. But of course, you can only do it the once.