Responses
Dark Heaven maybe
I have not read Lover Boy but here are some slow romances I've read:
(shounen ai - they never explicitly get together but it's implied) http://www.mangago.me/read-manga/komatta_toki_ni_wa_hoshi_ni_kike/
(webtoon) http://www.mangago.me/read-manga/the_priests_chart/
(shoujo) http://www.mangago.me/read-manga/keishichou_tokuhanka_007/
I love the slow burn romance/not actually unrequited love and the heartbreak