If you hold the phone on your side of the bed, it should theoretically record your sleep pattern, not hers. So it should play the alarm when you’re in light sleep, not her. And since the alarm starts off with low volume, there’s a high chance you will be the first to hear it - she might not even notice it before you’re already up. Unless you’re a heavy sleeper and she isn’t, in which case - yeah, it might not work.

The only thing I’ve tried that actually works: apps like Sleep Cycle.

The app tracks your sleep, but that’s secondary for you. What you want out of it is the alarm part. You give it an interval of time when you want to wake up, and it’ll do it based on which sleep stage you’re in.

The idea is simple - you have different stages of sleep. Sometimes you’re in deep sleep, sometimes in REM (rapid eye movement), sometimes in light sleep - there may be others, idm. You want to wake up from light sleep, that’s when you feel the most fresh. Waking up from deep sleep you’re all groggy and still half asleep. So the app determines when you’re in the lightest sleep, and it plays an alarm gradually, so that you’re not just scared awake.

You can read more here: https://www.sleepcycle.com/features/smart-alarm-clock/

The thing is, this feature is actually not why I got the app. I wanted to track my sleep, I didn’t really care about how I woke up. But I honestly just found it easier to wake up with this, so now I recommend it.