I am a very queer, very outspoken member of the LGBT community and am always looking for novels with queer themes. These are my favourite novels with such themes - if you want to read about authentic and realistic portrayals of queer relationships, this list is of you. 

LGBT characters and queer novels are often subjected to being fetishised by both the author and the fandom. There are sadly few books written by LGBT authors, FGEP is thankfully one of them (and you notice the difference!). The books on this list are not perfect, but that is impossible, anyway. But, I can wholeheartedly say, that they have good representation and are portrayed in a healthy, respectful way, most of the time  (which can't be said for a lot of other novels).

Last but not least:
As much as I love MXTX's novels, her first two novels especially are full of cliches and over-used tropes, while the story still remains good. An actual human being isn't defined by their preferred position during s*x - you are allowed to switch it up! I swear, Luo Binghe and Hua Cheng want to be topped so bad, I don't get why the fandom tries so hard to restrict them. Build an opinion for yourself and tread carefully - the s*x scenes are often... unusual, to say the least.