The plant is about 60 cm in a pot. The upper part of the stems which have flower buds on then, are drooping. There is no sign of pests, it has been watered and is neither soaked nor dry.
Why Is My Oleander Drooping?
Certified GKH Gardening Expert
Oleanders branches can become droopy if the blossoms are large and to heavy.
If you see not other signs of plant health, this is most likely the issue.
Pruning can help you correct and tidy up the plant.
If you seen any continued decline in health of the plant it could be Oleander Leaf Scorch.
Here are some links for you.