She won't have sex with you because she's been cheating on you for some time now. It seems like she likes what you're providing in the relationship (money, consistency, reassurance, "love," etc.),...

Totally normal, don't stress over it.

Recently went on, or got off, the pill? Any changes in your diet? Perhaps get your thyroid checked, could by hyperactive.

Watch it. Teasing strange men is a good way to get raped.