My ailing Peace Lilly

I came to a decision about my Peace Lilly: I cut off the dead flowers.

Now the one remaining tall flower is beginning to wither despite my much more frequent watering.

I still have a collection of smaller flowers, but they just aren't as beautifully imposing.

I'm worried about the smaller flowers too: if a perfectly healthy bigger flower can wither away with good treatment what's to protect the babies?

I'm coming to the conclusion that I'm a really bad gardener (or to put it more accurately pot-planter).

What am I doing wrong?

Is it just the time of year?

I need to know before there's nothing left to my plant but leaves!