Like in traditional romances, the hero's problems in yaoi and M/M romance are (1) settling down in a stable relationship; (2) repairing an emotional/mental issue.
Regarding (1), the tension between an open-relationship and monogamy is a real issue; scholarly articles discuss how the lack of a "given" here is still a difficult discussion in male gay culture.
My favorite solution to this "problem" (it kind of depends on the couple--and the genre) is from Fumi Yoshinaga's What Did Your Eat Yesterday? in which Shiro confesses to his friend Keiko that he stays with Kenji, to a degree, because the idea of going back on the dating market horrifies him. He is willing to invest in his partner, even though Kenji, on the surface, isn't the kind of guy he imagined himself ending up with.
Shiro isn't totally self-absorbed. He later admits to himself that before Kenji, he tended to date narcissistic creeps. Falling in with Kenji, almost by accident, was a lucky twist of fate.
The issue of "hero with mental issues" also haunts the literature. I have written here and here about why I find it so problematic in both yaoi and in M/M Romance.
Yaoi and M/M Romance have one advantage. Men, historically and now, are expected to have jobs, which makes their search for a job with meaning--or at least a purpose in life--a stronger part of the literature. A strong contemporary example is Kim Fielding's Love is Heartless in which outspoken, profane Detective Ng has a job and purpose, but his boyfriend--well-off Colin Westwood, who works for his father--has employment but no purpose. Colin finds it when he becomes fascinated by the older houses in the area and makes a case to his father to refurbish them, rather than buy them up and demolish them. This is not son versus father, by the way. The dad is a good guy who simply needs to be presented with a valid argument.
Kim Fielding continues her careful delineations of character in Love Has No Direction in which the one character's seeming lack of career is not a flaw to be fixed but a talent to be adapted.
In any case, the question, "What is this person going to do with his life?" gives the literature gravitas--which of course, brings us to all those Regency fops who supposedly don't have to work for a living.
They will be addressed in another post...