Looks like they need water. The soil around the shrub appears dry in the pictures and lack of moisture will force the plant to wilt/droop. If the lack of moisture gets worse, the plants zaps the blooms and these begin to brown out; if things continue, the leaves' edges will brown out and continue browing out inwards until the brown leaf falls.
Provide hydrangeas evenly moist soil and year around 3-4" of organic mulch up to the drip line. Meaning no periods of dry soil then wet then dry and so forth. To help determine when to water and to prevent overwatering, use the finger method: insert a finger into the soil to a depth of 4" (not counting the mulch) and see how the soil feels. If it is wet, figure out why (did it rain recently or did the sprinkler go off recently, etc) and take action to prevent root rot if the soil is not draining well. If the soil is moist, do not water. If the soil is almost dry or dry then add 1 gallon of water to the soil around the plant. It is best to water deep and not often. Test early in the mornings with the finger method or with a soil moisture meter daily for 2-3 weeks. Each time you water, make a note on a wall calendar. After 2-3 weeks, review the watering notes on the calendar and determine about how often you were watering: every 3 days? 4 days? etc Then set the sprinkler to water 1 gallon of water on that same frequency. In the summer months, you may want to add more water, say 1.5 gallons. When the temperatures go up or down 10-15 degrees, use the finger method again and see if you need to tweak things.
Once the leaves dry out when the plant goes dormant in the Fall, you can switch to watering once a week or once every two weeks as long as the soil does not freeze where you are. Remember to water in dry winters (if the soil has not frozen). Because they do not yet have a good root system, I find that it helps to hand water the soil once a week or so on year one (I do it in the summer only). A local plant nursery suggests that for camellias, azaleas, rhodies and hydrangeas even when one has a sprinkler or drip irrigation. I learned that lesson the hard way when I put new camellias, put drip around them (did not hand water) and they suffered because drip did not reach well into the roots.
Wilting like yours is very common on the first few years. Usually around the summer months though. Once the plant becomes established (1-3 years), these wilting episodes are reduced.... but never completely eliminated. Windy days and summer weather can trigger these. If you discover a case of extreme wilting, immediately give the plant some water (1/2 gallon) but otherwise, if the soil is moist, hydrangeas will recover on their own by night time or next morning. So what I do when I see wilting is to test the soil and it feels almost dry or dry then I give them 1/2 galon of water. Otherwise, I do not water and I let the plant recover on its own.
This approach helps prevent overwatering, which causes root rot. Plants like hydrangeas, if they get root rot, they will look like their soil is dry (wilted) because the rotted roots cannot absorb water and the leaves wilt.