려고

I'm planning to (trailing off)

Ends a line by stating your own plan and letting it trail away: planning to go for a walk, I'll take it nice and slow, I'm going to grill for you today, if I get rejected again I'll run away. The unspoken half is 'that's why' or 'that's what I'm doing' — the sentence is deliberately left open. Compare 을게요, which promises the listener something; 려고요 just reports what you intend, whether or not it involves them.

Register: casual to polite depending on the 요