Smooth starting screen.
I like the little backstory between the messages. It's not really realistic to a phone messaging app (I think), but I think it's helpful to have here.
The time period kinda made me confused at first, especially on the first year. I thought Steve messaged me in the present times, but after seeing it again, I realized he messaged me in the past. I think there should be a date on each message, or at least at the top of the chat.
I like the story and how it gradually unfolds. No obvious or blatant storytelling at the start that tells everything you need to know.
Should've made it an option for Steve's 25th birthday, but I guess having it auto replies is part of the challenge and the story. I legit had difficulty in replying to Mia's invitation because of that xD
That end with all of the "soon" messages is a really nice touch.
I really like how you interpreted the theme for this one. It really fits, how one simple message, one simple decision can lead to another and another.
The art style and UI is clean.
The SFX is really good. So is the music. Both fits with the theme of the game.