Neutered male not responding well to female puppy

Hi! I am looking for a little bit of advice.

I have 3 dogs. 2 adults and 1 puppy.

1 – 7 year old Female German Shepherd (spayed)

1 – 4 year old Male Lab Mix (neutered)

1 – 7 month old Dachshund (not spayed)

The German shepherd has been engaging in play with the puppy with no issues. My male has had a much harder time adjusting and does not seem to enjoy engaging in any sort of play time. When they are near each other, he barks at her and only wants to smell her private parts. He plays with the German shepherd just fine and doesn’t seem to mind her at all.

I should also mention he has never bitten her or even tried to bite her. Any time they spend time around each other, it is 100% supervised.

We have taken them on walks together which goes great! I was hoping to get the puppy spayed after her 1st heat cycle. Could her not being spayed be causing his hyper arousal/aggravated behavior towards her? When she gets spayed, will his behavior towards her possibly tone down?

We have been looking into helping him with some professional training for socializing and just better manners in general.

Sorry if this is all over the place and thank you!!