I have a two-tile window which I'd like to separate by putting a wall in between so each half would be in another room. The thing is it says "can't intersect other objects". Is there some mod or cheat allowing me to put this wall?

Can you put the wall up first, then put the window in, using move objects on? Then you'd probably need to save, exit and reenter the lot to enable the wallmask.

No. It won't work. Your best bet is to find a single window that looks the same on both halves and put them on each side of the intersection wall.

Build your rooms, place window with moveobjects on - use the hammer tool to delete the first part of the wall right in front of the window. Then undo that by using CTRL+Z. You should end up with a window with a wall in the middle of it.

This also works to place fences and half walls.

Now that is clever @mustluvcatz !

I tried this and it worked fine.

That picture looks so Sims 3-esque

I don't even use the hammer, I place the window with move objects, draw the wall and click undo. I think that's what i do, can't recall if i draw the wall first or place the window first. Lol nearly midnight, I'm asleep.

Sorry all, it never works for me in the past.

Seriously? Why are you doin' this? I never place window like this. Because it looks odd when you look in the window from outdoors.

Not sure what you mean, I was saying how I remove a wall mask.

If you mean it looks odd when you leave the wall, well yes it can, you do have to pick the window carefully. Not any old window will do.
If you read my post you may notice I said to undo the drawing of the wall. I was talking about when you place a window but you see the wall mask. I was half asleep and had not read the OP's post well. Only I noticed MLC saying she used the sledge hammer, but clicking the undo button works just as well.

I mean that I will never place the wall in the middle of the window. In any case. That's my opinion.