I have no problems with aphids on mine cuz of the praying mantis I have. I see at least a dozen around everywhere in my yard.
Just the other day I saw a large female with a huge egg sac.

How about ants, do you notice unusual ant activity? When you wash them off and they reappear like magic, you may have some ants helping them. Al

I have had the same thing happen with those yellow milkweed aphids. I think they grow out of thin air. I finally got rid of my milkweed!

Exactly Renee! It's bizarre how fast they return and so thickly clumped around the flower stem. I have enjoyed seeing the bees attracted to the flowers but I might let the bush go.

The aphids have just been relentless on the bush. Probably could spend $8 on some spray, but no thanks to that.

OK, just for the record, here's what I did with the bush:

Decided to let the bush die and so stopped watering the pot.
It wilted badly, needless to say.

Then I felt sorry for it and watered it.

Chopped the whole thing down to about 6" with 1-2 tiny leaves.

Remembered someone had luck with worm castings and whiteflies, so I put about 1/2" of worm castings on top of the soil.

The bush has resprouted, has a little bloom, and no sign of the aphids.

Not sure what worked here--maybe the dry soil, maybe the chopping down, maybe the worm castings. But I hope it continues to do well.