I cannot see an obvious reason why this should be but could the problem be that there is a lack of water. The surrounding grass is acting like a barrier and soaking up any rainfall so starving the roots of moisture. Perhaps create a circle of clear soil around your shrub so rainfall can penetrate the soil and get to the roots. A light prune to reshape the shrub and a really good watering.

I cannot see an obvious reason why this should be but could the problem be that there is a lack of water. The surrounding grass is acting like a barrier and soaking up any rainfall so starving the roots of moisture. Perhaps create a circle of clear soil around your shrub so rainfall can penetrate the soil and get to the roots. A light prune to reshape the shrub and a really good watering. Sorry sent twice.

alternatively after all the rain recently is it waterlogged?

if it is very wet underfoot, fork the ground around it to help drainage.

It may well recover.