Have you ever had nights like that together? If so, I assume you really enjoyed having that time with him, and miss it. If not, you could just be seeing how relaxing and fun it is for the others when they get it, and are feeling the need for similar relaxing/chill time. Hell, maybe you spend your dates catching up on joint chores or something and are just dying for a long enough block of time to fit in some fun with all the mundane stuff.
So it might not even be envy of Lamian or Peaseblossum at all, and I sure wouldn't call it jealousy. I'd just say you're craving something, and I'd just tell my partner "Hey, I'm really finding that I'd like X type of time with you, is there a way we can fit it into the schedule (regularly or occasionally, whichever you think might fit the bill for you)?" And then you two, or all four of you, juggle things around for each other.
Happiness will never come to those who fail to appreciate what they already have.