Should I date someone if they're still not divorced?

Don't do it. In this situation you risk finding out later that it's not a serious relationship, just some fun on the side. Plus the emotional mess - his wife, then your disappointment when he changes his mind. Better to wait until the person completely closes that chapter of their life.

I know a couple who started dating when he was still married - like, they weren't together anymore, but the divorce was dragging on officially. It took five years before he finally went through with it. During that time she spent tons of time, energy, went through so much doubt... and in the end they just split up because they were exhausted. So the risk is real.

But the main thing is to figure out what exactly bothers you about his situation. If he says he's been living separately for a while and the divorce is just a formality, you can ask for specific timelines. Not promises, but actually see that the process is moving. Call it a boundary - if nothing has changed in three months and he's just rushing to hide this whole thing, that's a bad sign. If he's being upfront and honestly tells you when his court date was, you can even ask for it to be finalized as a condition for getting serious.

One more thing: ask yourself if you're attracted to the fact that he's unavailable. When there's an obstacle (a wife, a long divorce), it can feel like the feelings are stronger than they actually are. Once the obstacle goes away, it often turns out the relationship wasn't that solid to begin with. If this person only matters to you right now and in this exact situation, that's worth thinking about.