I've just gotten back into rewatching DS9 after a long hiatus. I have to say I liked the Garak/Ziyal relationship. I'd forgotten the multi-actress casting situation. I get why they went with Melanie Smith from an age standpoint. She didn't really seem 35 in that makeup and Garak seemed younger to me than Andrew Robinson in real life so it wasn't a problem from that standpoint.
In "Call to Arms" she kisses and hugs him on the way off the station, and Garak seems startled not by the idea that someone he doesn't have feelings for is kissing him, but that she feels a genuine love for him and an honest spirit when he's used to so many people having ulterior motives. He's holding her the way you do when you feel something for someone--even if he doesn't think he deserves to receive it, and even if it's not grown into love. He feels something, but with Garak it's always more complicated than that.
In "Sacrifice of Angels" he's among those reuniting with loved ones on the station, looking for Ziyal. It's not like he's just humoring her, knowing she expects to see him and he has to go through the motions. He's not just going to be relieved to see the other DS9 Cardassian is safe or that his friend's okay. As much as he likes Bashir, I dunno that I'd ever expect to see Garak looking around that way, anxious for a reunion. Ziyal feels about him the way no one else does. He's looking forward to seeing her, knows she'd be looking for him, and genuinely wants to reconnect with that innocent soul that thinks he's a wonderful person. He would've been happy and relieved to reconnect. I think that says a lot. We can't expect him to break down in tears in the infirmary. Kira wasn't doing that. They've both seen too much death and lost too many people.
If nothing else, he'd eventually have the My Fair Lady realization "I've Grown Accustomed to Her Face" and if his neck was on the line at some point in the future she'd try to stand with him rather than let him be scrappy on his own. I'm not sure if Garak thought he deserved to be loved by someone like Ziyal. That's why he couldn't figure out why she loved him. It wasn't some weird attachment on her part. It was that he didn't understand how he warranted anything like that from anyone, especially because his life has been lacking in trust for so long. Kind of sad.