I know what to do to help, but I am not convinced you are really wanting this with the kind of woman who will cheat on you, then worry you whether YOU will let her down or some such thing.
If you want this woman to be on fire for you, start by making it as so that it would be practically impossible for her to have sex with you even if she tried very hard with all her might and begged you on her knees.
Otherwise, she is using you terribly, and as long as you allow this, she will not see you as a sexual partner, but a roomate or a little brother.
Now, there is no respect to you from her.
Before sexual attraction, there must be respect.
Even though you are married, and have had I assume some healthy sexual relations in the past, it is not uncommon for the married man to wind up in the "friend zone."
Avoid the "friend zone."
Friend zone discussion: But If We Started Dating It Would Ruin Our Friendship (satire)
Respect, then sexual attraction. These threads are this: The Man Up and Nice Guy Reference