The slow romantic pace is because Mrs. H was a married woman and is a religious woman
Now Mrs. H is free to consider marriage and romance. Even with Gerald, she was still married. It takes time for her to consider herself free to marry.
Also, Seigfried maybe isn't the catch he thinks he is, or he would have been swept up sooner. And maybe he's thinking Mrs. H is the woman for him. If so, he should make a move before we're bored of the whole thing.
Married life with the two would be interesting. The actor sells the storytellers short in that quote in the newspaper. And the shift would be to telling stories of the Farnons interaction with the townspeople and the animals. That's always interesting.
That Mrs. H is employed at the house might be more of a hangup, but a very slight one when they're all country people with fewer people to date. And when there's a war on and lives could be cut short because of it. Put a fire under it and propose already.