Royal Fiancé ...Mayb
Some of these are shy, but not during sex.
http://www.mangago.me/tag/Shy+Uke/
Sick is shy for both, so that's what I've read that fits your description the most.
http://www.mangago.me/read-manga/twins_labyrinth/
http://www.mangago.me/read-manga/kimi_ni_sachi_are/
http://www.mangago.me/read-manga/hana_no_mizo_shiru/
http://www.mangago.me/read-manga/omae_wa_hitsuji/
http://www.mangago.me/read-manga/kokoro_kanda_neko/
http://www.mangago.me/read-manga/bukiyou_na_silent/
http://www.mangago.me/read-manga/emono_no_kimochi/
http://www.mangago.me/read-manga/hanamuko_san/
http://www.mangago.me/read-manga/kaitou_game/
http://www.mangago.me/read-manga/mimitabu_no_riyuu/
http://www.mangago.me/read-manga/kafe_kara_hajimaru_love_life/
http://www.mangago.me/read-manga/kawaii_hito_pure/
http://www.mangago.me/read-manga/count/
http://www.mangago.me/read-manga/motto_hanashi_o_shitai_no_dakedo/
http://www.mangago.me/read-manga/joushi_tono_hitoban/
can i have a yaoi recomendation where the uke is shy but the cute kind of shy and when they have sex the uke is shy as well