If you liked the Rules manga, the Anime-Planet community thinks you'd like:
These are subtle romance stories between males handled in such a way as to avoid yaoi clichés. Rules and Dear Green offer believable casts in real life situations with an emphasis on character development. Both are highly recommended.
Rules and No Touching at All are very realistic romance stories of homosexual love. Without borrowing from cliches they offer a powerful balance betweem drama and daily life in such a way that attests to a genuine desire to spin tales that could very well happen. These are manga that do away with flourishes to get to the heart of matter, to develop relationships between characters that are highly believable. This is slice of life at its best and romance at its most moving.