Sorry, I'm not good with the syntax, but why is this not (e.g.) "Mae Megan yn fy ngwraig"?
Excuse my ignorance of syntax, but why isn't it (say) "Mae Megan yn fy ngwraig"?
When discussing names, occupations and roles, the usual pattern is the emphatic one, with the name, role (such as wife, husband,...), or occupation coming first in the sentence.
(See the section notes for 'Greeting2'.)