 Why does Matilda break off her engagement with Herman?
This, in itself, was not unusual—but Matilda was so completely wrapped up in the romantic fallacy of her day that she sought a prince charming, a faithful Don Juan, a man who had been everywhere and tasted of every worldly pleasure and who now wanted to sit on a porch and talk about it all to Matilda. The first thing the widow Penshaws did was to take Matilda's left hand in her own and examine the next-to-the-last finger. I gave him his ring and said thanks anyway and he smiled politely and said he wished I had told him sooner because his fifteenth college reunion was this weekend and he had already turned down the invitation." "But, Matilda, that's your fifth broken engagement in three years. Matilda switched her bed lamp on and dabbed some citronella on each ear lobe and a little droplet on her chin (how she hated insects!). Someone in Nebraska wanted to trade match books; someone in New York needed a midwestern pen pal, but it was a woman; an elderly man interested in ornithology wanted a young chick correspondent interested in the same subject; a young, personable man wanted an editorial position because he thought he had something to offer the editorial world; and— Matilda read the next one twice. Cedar Falls was a small town not fifty miles from her home, and she'd get there a hop, skip, and jump ahead of her competitors, simply by arriving in person instead of writing a letter. Matilda got out of bed at seven, tiptoed into the bathroom, showered with a merest wary trickle of water, tiptoed back into her bedroom, dressed in her very best cotton over the finest of uplifting and figure-moulding underthings, made sure her stocking seams were perfectly straight, brushed her suede shoes, admired herself in the mirror, read the ad again, wished for a moment she were a bit younger, and tiptoed downstairs. Driving the fifty miles to Cedar Falls in a little less than an hour, Matilda hummed Mendelssohn's Wedding March all the way. First place, I don't know any Haron Gorka—" Matilda kept the alarm from creeping into her voice. Twenty years from now, this could be Matilda Penshaws—complete with plain gray dress, rimless spectacles, gray hair, suspicious eyes, and a broom-stick figure.... "If I can't enjoy an association with Haron Gorka directly, I still could get the vicarious pleasure of your contact with him. Each one of you will tell me about Haron Gorka, sparing no details.
 He was too “stuffy” for Matilda.
 She’s looking for someone more adventurous.  He was too “stuffy” for Matilda.  She doesn’t want to settle for him, as she’s too fixated on the idea of romance she has.  She’s afraid of commitment, as is hinted by this being another broken engagement for her.