The pronunciation is like your first one and I definitely stress the 'elle' ending.
I've considered
Marielle Eve since I adore
Eve. I was just unsure how I felt about the two vowel sounds running together. I do love your suggestion of
Marielle Celeste which has a beautiful flow to it.
"Darkness cannot drive out darkness; only light can do that. Hate cannot drive out hate; only love can do that." --
Martin Luther King, Jr.