It is established that the player and SH are exclusive at the end of act 2. Plus most people will assume she means she wants to be with you now and always, as meaning only you. You may look at things differently, but the vast majority would take this as meaning monogamy.
I'd say the conversations where she forces you to pick between her and <other origin companion> are even more telling, but yes, this too, just to a lesser extent because if you really feel like reading between the lines you can still find ways to say "Nah man she meant otherwise" even if that would be blatant bad writing.
