It's an even more fine line than that... I'd actually say... that line doesn't even exist... it's a self imposed false flag, for you...

If your W truly is depressed, as in could be diagnosed as chronically depressed... this is an internal battle she is fighting for herself... and she's scared... terrified, in fact... and she's likely to lash out at anyone who tries to make her face her fears...

Support her in going... no encouraging, no writing things on the calender, no subtle hints... and no expectations...

If she doesn't go, do not mention it. If she doesn't go, then later says she's decided to go (again), no telling her "great to see you changed your mind"...

BE THERE for her... BE WITH her... and support her, silently... and with love...

And, if she goes, acknowledge it calmly and sincerely and NOT with enthusiasm, IF she brings it up... soft support might be a good path, atm...