Yep. I want some yaoi manga with both seme and uke is hetero. But, accidentally fall in love with a man (uke/seme). I hope there's a good development about their relationship.

Haru o Daite Ita is probably the most famous example.
Here're the straight seme + straight uke search results.

Hrodulf and Bjornolfr, you will not be forgotten.
[img]http://i411.photobucket.com/albums/pp199/SyberAngelGabrielle/couplesig.jpg[/img]
[color=black]And if the world were black and white,
you would be my rainbow in shades of grey.[/color]

Click 'n Play!

If I had a fantasy self, it'd be a tentacle monster.

Try 50x50. Its a pretty fun and short manga 😃