Is it possible to stream music with my apple watch series 2 over wifi?

Hi

No, I'm afraid not.

Streaming is supported on Apple Watch Series 3 models.

You can still sync tracks to your Apple Watch for listening to via Bluetooth headphones or a Bluetooth speaker paired directly to your watch.

More information:

Listen to music on your Apple Watch - Apple Support

Play music

Connect Bluetooth headphones or speakers

Add music to Apple Watch

If you would like to submit a feature request to Apple, then you can do so here:

Feedback - Apple Watch - Apple

(You are not talking to Apple here - this is a user-based technical support community).