[queeneofthemay]

It was set in a Victorian-style Londen and involved a rich lord who was supposed to marry a woman who ran off to marry her lover. Her younger brother dressed up as her and married the lord, who after finding out about the deception fell in love with him and they kept up the deception as a male and female married couple in public.

I believe it came out in the last five years. Help?

[dante11]

it is ''the crofton chronices'' by rebecca cohen

[queeneofthemay]

Nope, that's not it, but the books do look interesting! Thank you for trying!

[queeneofthemay]

I took a second longer look and I do think you have it right, after all, I recall the name Sebastian now and it fits! Thank you!