I swear I read this manga before, and I'm pretty sure it's by Chi-Ran, but I didn't find it among the other titles. A sweet young doctor (uke) falls for another doctor who is very cold and in love with someone else, who he considers his number one. So the uke works hard to fill the number two spot. <--I just realized what I wrote... Oh yeah, I think the story contains like bondage and toys and stuff.

The uke has a terminal illness, eventually dies, and by the end of the story, the seme did grow to love him.