A bit of speculation here, not about what it means, but about where it came from. If you listen to old delta blues, you’ll hear phrases and entire lines and verses attributed to one song writer that appear in songs by other composers. I’ve read that a lot of blues songs were not so much written as they were assembled from parts that were simply the common vocabulary of the blues. Some of these phrases are quite mysterious to modern ears, but had an accepted meaning in their time. Check out the lyrics of Robert Johnson for examples here. Although “love comes tumbling down” isn’t in there, you’ll see lots of phrases that it’s hard to discern the meaning of. Anyway, I believe that the phrase may come from the delta blues tradition, but searching out its origin is beyond my capabilities. More recent use of the phrase simply causes too many hits for a web search. Maybe this is a job for Cecil. He handled “pompitous of love” nicely.