At the start of the first film, she tells Imhotep to save himself when the Magi are coming. When he tries to stay, she tells him that only he can resurrect her and when the guards come, she stabs herself.

Now you can argue that she knows Imhotep will save her and she feels she's at no risk, but that's still a hell of a thing to do for someone you don't love.

The voiceover at the start also says that they were willing to risk their lives for their love. So to me, it's pretty conclusive from a character standpoint.