As someone that ended up having a lot of sex in his situation, this advice is spot on. As we always say, being 100% sure she is not physical with anyone else is paramount! And then as BL said, if you cannot do AND still continue to work on detachment, then you need to be careful.
For me the sweet spot was to realize that she could walk at any minute, including 1 second after we had sex. That sex had no meaning related to her wanting a D. That it was just purely the physical act with little to no emotion behind it. In my case, it was really about her having a lot of pent up sexual energy due to her EAs with guys that were hundreds, or 1000s of miles away. AnotherStander and sandi (I believe) pointed out to me that likely she was fantasizing about her EAP while making love to me. That was a very sobering thought. One that did give me pause a few times.
But as BL said, the sex can, and for most LBS will, hurt your detachment. We've seen a lot of LBSs that have had sex throughout their situation with the WAS, some even while the WAS was sexually active with other people (SMH), and it is a very rare LBS that can do that and NOT attach significance to it.
BL is spot on with this post.
I remember reading one of your early threads and encountering the bolded part (above), and thinking about that in regards to my own situation. Yeah, it's not a pleasant thought, but whatever...what can you do?
Another thing I recall from probably the same thread, Steve, was when you got to a point where you weren't sure if you wanted the MR anymore yourself. I have had a surfeit of such thoughts myself recently - not actually putting real consideration towards being the one to leave, but an internal temperature check of marital satisfaction. And there's not much there. Like LH19 said, he was glad his EXW didn't actually waver in the face of her father's wrath, because that would mean he'd be stuck in a dead marriage today. I've been trying to gauge my detachment efforts from W by comparing interacting with her to a trip down to the mailbox (analogy courtesy of Mach1). I guess all this is to say that sex is losing any emotional significance...the last dying embers of the marriage are barely glowing.