I've noticed sex definitely feels better during that time. Many years ago, I was getting fucked from behind and it felt so amazing, I started to cry. He was like "What's wrong?" hehe
Crying during sex has only happened a couple of times in my life. That's when it feels incredible...
I'm sure you will find it no surprise in the slightest when I say the reasons hormonal. It's very common for women to experience an increased sex drive and sexual enjoyment around that time of the month. I've had it happen too.
The crying during sex as you likely already guessed is probably your usual inexplicable emotional swings caused by the significant changes in hormone levels we experience every month.
I have a bit of a pet interest in human reproductive biology. Especially the insanity that is the female reproductive system. God musta been high when he was coming up with how ours was supposed to work. Made it all so simple to start with for the boys then decided to get "creative" for round 2. That is if you subscribe to the men are from dirt, women are from a leftover rib way of thinking.
Personally I'm not religious but I gotta admit, gods existence and men being his first go based on his own perfect image, followed by hastily getting women out of the way to use up the left overs would sure explain a lot about female human physiology. Like botching childbirth so it's dangerous and excruciating or so screwing up our reproductive system the smallest thing will break it (I dont even get my period most of the time cause heavy heroin use breaks it, we have the pill and not the boys cause their reproductive system actually doesn't totally fail because the humidity is a little high or something. Whereas ours suffers a total failure to function properly if some made the mistake of looking at it wrong. Even when it works properly it breaks our emotions instead. Until it finally breaks down for good decades before the intended operating lifespan of the rest of the female body and as a final fuck you often takes out proper bone maintenance in the process.
That's some damn compelling evidence that god exists, and that he's indeed a he. That or evolution was surprisingly selective when handing out developments that didn't quite work right. Except for making us pleasing to look at, suspiciously that turned out fine
I joke but you gotta admit it makes a surprising amount of sense when you think about it. Humans are dicks, god is a massive dick. And if an intelligence really did have a hand in humanities creation, it was a total dick, especially when it came to the humans it made without one.
now for some reason I am not as keen on it, I guess we all go through phases 
