No, they definitely are arsed about it, they have to for many reasons, including but not limited to;
Push the Russian Black Sea Fleet further from Ukraine's mainland by taking control of Sevastopol
The natural resources of Crimea are huge, Ukraine want them including the oil and gas
They have promised their people that they will take Crimea
There will never be peace in Ukraine until Crimea is retaken and secured
Not retaking Crimea will represent a form of winning for Russia