Earlier quoted context omitted.
She says she wants to get in shape but actually she likes visiting new gyms. Nothing wrong with that, right?
She is a gym member maybe 1 out of 3 months because she is perpetually rotating through the deal she can get. The secret to this stuff is boring - persistent, continuous effort. If you can't even maintain a regular gym membership, you will not get that effort in. She's been complaining for over a decade as she continuous this charade.
Maybe she’s actually staying more motivated to go this way, maybe her engagement is higher than if she paid. Or, maybe she’d love it if you gave her a gift and pre-paid for 6 or 12 months of membership somewhere? You could even tell her you got a deal, which is true regardless of what you pay. Valentine’s Day is here…