How do you grow them? Inside, outside? What kind of lighting?

Responding to my own question and in answer, I grow them inside. I live in Missouri. I have grown the same one for years and it has bloomed fine for me. It gets good light on a stand in an east window with a little bit of south light, indirectly also. It is an orange with white stripes amaryllis and it is a double flowered type. This is just the first time that something like this has ever happened to me in growing and blooming it.

can you give me an image? How is its leaves?

By all appearances, it is a normal, healthy amaryllis. The leaves are a healthy green. They are not flopping over. I have grown and bloomed this same amaryllis for several years. I have had good luck each year. It's just that something went wrong this year and the flowers flopped right where they join the blossom stalk and they did not last very long.

Sounds like they bloomed fine but did not last as long?? maybe it was in too much direct light? Even up here in the Twin Cities that late winter/early spring sun can be really strong if it was still in that window. I move mine to the dining room table away from the window when in bloom and they last about two weeks-

"it seems like the stems of the flowers got soft and drooped "
"I grow them inside"
I don't think this is a matter of light.
Even when I planted it directly in the sun in the summer, it still bloom about 5 days, not soft and droopy.
I think this is a type of fungus. no ventilation for growing, high humidity can create conditions for fungal development.
next year everything back to normal.