With my current fluid bonded, playmate I know he came, if for no other reason, because he always says, "Stay there, Love. I'll be right back." Then he returns with two washcloths. The dry one he uses to wipe his semen from my belly and vulva. The other is hot and wet, and he cleans me off, starting from anywhere he's sweated onto me, and ending with wherever he's made his deposit.
I know when it's impending. He could be hard as calculus, but he starts to feel somehow, impossibly, harder. His rhythm goes slightly off. I feel his balls tightening, depending on our position. His breathing is ragged. He responds to sweetness and affection; hearing that I love him, a gentle kiss, or gently mopping the sweat from his brow will push him right over. In fact, a lot of the time if I'm just trying to be thoughtful about something, he goes from affectionate touching to lust machine instantly.
We don't want to reproduce, so he's only ejaculated inside me once. It felt very warm, and in addition to the spasms, I could feel the impact against my insides. Then, of course I felt very slippery, too slippery.