You know what I did? When I just felt I HAD to say it to H, I said it at times when he couldn't answer me - therefore, no pressure for him to say it.
For example - signing off a phone call - "Bye, H, love you (click)". I would click quickly so there would be mno awkward pause or pressure for him to say it back.
(I also used to whisper it in his ear when he was sound asleep )
)