Ever since yesterday's chapter I couldn't stop thinking about this, so I'm just publishing this to have some piece of mind.
Vine has a thing for praise, and yes even in the bedroom. It started mainly because Gale is super affectionate and loves to praise him all the time. Especially in the bedroom because he wants to make sure Vine is okay and that he knows that it isn't just about sex. The praise just really helped Vine a lot, and now it's just a thing.
Thank you for coming to my cursed TEDTalk.