Man, there are so many different ways to show love/affection but here’s a few. For expressions, I mainly focused on eyelids and mouth. The dreamy eyes and slight shy smile come to mind with anything lovey dovey but also being nervous, curious, confident, sense of longing too! Not to mention flirty and love sick! Remember, the character is interested in someone/something. Placement of eye becomes important to show the interest!
As for poses, ah! Just keep in mind if you’re drawing two characters interacting- consider their relationship 8) Hope it helps!!