Higher diastolic values - what could be the cause and remedy

Hi! My wife was diagnosed with hypertension a couple of weeks ago with her blood pressure frequently being in the range of 135-140/95-100.

She started to make some immediate changes with 20 mins cardio every morning and magnesium supplements and we start to see some reduction already with values in 125/93 and also 125/85 at times.

However, I have noticed that her diastolic is frequently higher as compared to systolic. For example today after a 30 min workout and household work, her bp was 107/80.

So my question is what could be the cause for bigger increase in diastolic and how would we remedy it?