In historical romances, there is built-in erotic tension since propriety, social mores, and social expectations keep the characters apart. Against this is the main characters' overwhelming, unstoppable, unthinking lust for each other, a lust that cannot be denied (except, of course, when it's just wrong due to age or marital status; as Meatloaf says, "I would do anything for love . . . but I won't do that.")
This is a perfectly respectable plot and can be handled well. However, it does leave one with the slightly squeamish feeling one feels about any "trap." What if they realize, "Yikes! What a huge mistake!" Kind of too late.
With historical M/M couples, this "getting caught in the act" is not a fall-back position. Getting caught won't involve raised eyebrows, rumors, scandal, and a forced marriage. It will entail jail and death.
The lessons of Oscar Wilde have been well-learned. Being jailed on behalf of a petulant lover doesn't lead to an HEA (Happily Ever After), which is how all respectable romances end. Being jailed on behalf of a petulant lover leads to loss of rights, illness, despair, boredom, and, after being released, resentment, blame, disgust, and death.
Consequently, historical M/M couples have to be smarter, cleverer, more circumspect, and more thoughtful than historical heterosexual (i.e., traditional) couples.
Many historical fictional M/M couples resolve their "how do we get together despite legal ramifications?" problem through wealth, which is frankly somewhat irritating. That is, one of the members of the couple turns out to be wealthy enough to bribe servants, buy a separate residence, and take the pair abroad. I'm happy for them but what about the people who don't have huge bank accounts?
Some couples/writers solve the problem by having amazingly understanding family members, which is sometimes believable and sometimes not (depending on the family's background, whether bohemian, aristocratic, or thoroughly middle-class).
And many of these couples resolve the tension using smarts and/or mutual compromise/understanding. Abstinence--forced or otherwise--becomes not merely a social convention but a literary tool for exploring beliefs, roles, personalities, and future goals.
These issues are important aspects of all relationships from historical to traditional to contemporary. Unfortunately, they lose impact in modern writing due not to their actual lack of impact in reality but to writers failing to think through the problem.
Jane Eyre's unease around Rochester is lost in the off-hand modern assumption "But of course, these days, they would sleep together and nobody would care." But that's not the point. The reason Jane Eyre and Rochester stay apart is not merely social convention. Yes, Jane wonders what living with Rochester as his lover would be like (she and Rochester would have to go live in France or Italy). But her true concern is Rochester's ebullient, in-your-face, non-stop personality. If Jane has a thought in the days between the engagement and the first wedding, it would be "Slow the hell down!" (ah, Meat Loaf where are you when we need you?).
This is lost in the modern insistence that the "real" tension is sexual. And part of it is--as Bronte acknowledges--but it isn't all of it (or it is and isn't at the same time).
Unfortunately, the complexity of I-want-this-person-in-lots-of-different-ways-and-I-don't-know-if-any-of-those-ways-fit-me-and-my-future decision is often lost in contemporarily-written romance fiction where love conquers all. Historical M/M forces some of those issues back on the table:
What is a person truly willing to risk? And for what?