"it is my very ardent desire to be permitted to pay my addresses to you" 
 "Do you know, it has of late become an ambition of mine to hear my name on your lips instead of my title" 
 Yes, this is why we love Regency romances, don't we ladies? ;-) 
 "The Reluctant Widow" isn't typical / only romance. I would rather say it is first of all a mystery book, with spy, secret entrance, stolen document and so on. Secondly, it is a funny story where characters cope with extraordinary circumstances and events. Thirdly, we find here brilliant example of brotherhood (relationships between three different brothers). And fourthly, it is Heyer's romance. 
 I had fun reading how characters coped with mystery and I felt this sweet pleasure when the love story came to the end (through almost the whole book it only hung in the air, as I wrote it wasn't a main thread). But most of all, in my opinion in this novel the most original and praiseworthy was (mentioned above) description of relationships between adult brothers.