He's making an effort--saying Happy Anniversary twice, kissing you, giving you a back rub. I think you mentioned one of his fears was that you could never forgive him. Are you happy he's there and trying? If so, I'd reciprocate in some way, even if it's as simple as making a dinner he likes, a scalp/foot massage, watching a grown-up movie with wine, etc. Something to show he's on the right track.
My GF is working through that I dated someone else. She's learning it's okay for it to feel hurt, for her to recognize and let the feeling pass through her, but she can't dwell on it. I don't expect her to pretend to always be happy. I wonder if you can similarly show your life is happier he's returned, even if it doesn't wipe away all the pain, even if he's not talking about the affair so it's not the reconciliation you want yet.
