Wow, the art is incredible!! I wish I could apply, but I don't have practice doing scripts, (Only a little experience in storyboarding) though I do love progression fantasies and romance time to time.(I like to dip my toes in different genres and write in them.) However, I'm more of an editor than a writer, so if you ever need an editor, I'll gladly help out. Based on your webtoon, it seems like a project that I would enjoy.
Currently I'm working on a personal project, Ethra, where I try to incorporate the writing of the community into a progression fantasy story. @EncryptedWriting participated in the ongoing project, among many others, and I can vouch for them. I barely needed to edit their excerpt before queuing it to be published.
Also, just a tip, since your profile says you're new to the forums. You can check a forum user's post history. This might help you find out whether or not the potential collab person is a good communicator, native English speaker, and someone who can handle criticism.