When you're short on space, a cliché or trope can be the most efficient way to do what needs doing and move on to the real story.
Drafting is engineering and construction. Revision is art and design.
Craft your HEA to fit your characters. Let them surprise you with the innovative solution they all come up with.
Characters take an approach of "How can we make this work for all of us?" rather than "It's too bad I have to choose one of you."