Normally I'd give a couple paragraphs on how good the Marlin X-7's are, which, they are Awesome...as you're already aware!!
You could let her know that more weight means less sharp recoil...or that the factory recoil pad on the Marlin makes it feel so sweet, as you already have one
And you can also show here the Boyd's Riflestock options for the X-7 series and let her know that they can also be stained Pink or any other color... Original Replacement Stocks for Marlin Rifles
One thing I'm curious about...the Marlin in .243 is rated at 6.25 pounds,
and the Axis is rated at 6.5 pounds...So how is the Marlin Heavier???
Or is it a balance thing??
But it is..."her primary rifle"...which means, for better or worse, its her choice.
If at all possible, find a range that rents and let her try 'em both
The Axis, if you get the Bushy Scoped combo deal...get ridda the OEM rings and get some GOOD rings...the OEM ones SUCK.
The bolt ain't fluted like the Marlin, so that's something else to deal/not deal with...
She'll also probably want a RifleBasix trigger or some other aftermarket, as the OEM also sucks, it ain't one of the adjustable Accutriggers...
Or you can fix it like this...gently hand-polish where shown and replace the trigger return spring with a lighter one...might make y'all happy...
Other than that, it is a good rifle, and made in the USA