i think it's something you should bring up with her directly, and encourage her to discuss with her treating doc. my doc was always careful to make sure i hadn't "lost my libido" (i was 20 at the time, and nearly died when he asked me how it was going) and i know there are other ADs out there that might have less of a disruptive effect.

of course, with depression, it's also possible that this is just on of her symptoms. e.g. loss of pleasure and interest to do things. i think the best way you could support her would be to not put pressure on her to do sexual things, but maybe do sensual things together - to keep that physical intimacy? e.g., give her a massage, and vice versa.

the sex will come back.