Answer: East Friesland is usually stiffly upright without staking. However, if overfertilized with nitrogen and/or grown in deep shade it can flop over. Also, after the first flush of bloom, they need to be trimmed back to stimulate fresh new growth. This should stimulate additional blooms later in the season.
Based on your description I am not sure if any of the above would apply or not. It is also possible that there is a disease or insect problem causing the stems to collapse (this would be pretty unusual) or that they are badly overgrown and need to be divided as you mentioned. This is usually done in early spring (or September) and midsummer would definitely not be a good time to divide them. Typically it takes until the third year to need division unless you bought very large plants. Sometimes too a heavy downpour can break or bend stems and make plants flop.
Since they are flat, I would suggest trimming it back to encourage the new growth from the base.
I hope this helps you troubleshoot.
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