Well - it's a good match of instruments.
I'm not a composer, but have a listen to some existing romantic music for clarinet & viola.
These - by Bruch for a start.
And of course, Brahms transcribed his clarinet sonatas for viola himself (I'm a violist and my dad is a clarinettist, so I like to say that Brahms 'improved' the sonatas in the 2nd draft)
Going back in time a bit further, there's Mozart's 'Kegelstadt' trio for viola, clarinet & piano.
I'm sure I've played other things for the combination too, but a listen to some of the above might inspire you with the rich tones and textures - perfect for a budding romance!
K.