OH you are not being at all unreasonable. The devil is in the details.
I divorced my first husband on the grounds that he would squash peas on the back of his fork to eat them, the lunatic,
I ended another relationship because he said 'haitch', the fucking chav.
My second husband died in mysterious circumstances, but I won't forget his irritating laugh no matter how hard I try.
I lost a good friend to her insistance on her stupid Liverpudlian slang - every noun must be truncated and 'eeee' added on the end: the offeeee, the disheeeee, the compeeeeee, ffs was she raised by Jimmy fucking Corkhill.
I fired an employee on the grounds of their 'character' socks - Homer Simpson has no place in my office, be it on a t-shirt or a sock or in bloody person, which brings me to husband no 3.
It is entirely reasonable to end a relationship with a man who acknowledges his mistakes and misdemeanors with the word 'Doh!'
OP you have done well not to have the ridiculous Welshman shot. And you're not at all racist, oh no.