No deal if it sounds too different, deal if they still flow together nicely (like Rosfrith & [name_f]Elizaveta[/name_f] are from different cultures but have a similar vibe, so that works; but Rosfrith & [name_f]Callie[/name_f] sound too different).
[name_f]Natasha[/name_f] - you and your friends are big watchers of [name_u]Marvel[/name_u] - your partner admits that he totally has a crush on [name_m]Black[/name_m] Widow.