Leading partner's suit
If partner has bid a suit it's normally a good idea to lead that suit. But we're not leading it to keep partner happy! - We're leading partner's suit because it's likely going to be the suit with our greatest combined length.
Our job is not to make partner happy, our job is to defeat the contract.
Some players always lead the top of partner's suit. That's a mistake. If South leads the ♠K on this hand then East will eventually win a trick with the Q.
If South leads a low spade, the defence will take all 5 spade tricks.
The reason some people like to always lead the top of partner's suit is that it shows their holding in that suit. But as we've seen on this hand it often gives away a trick. Low from an honour also shows your holding in the suit so you're still getting the message across, it's just that partner needs to think a little harder. Well, partner, if you want to defeat more contracts then you're going to have to do more thinking!
Stick to the usual leading guidelines and you'll find yourself communicating really well with partner.