When dancing international standard with tall women (just 1 to 2 inches shorter than me), when making a big forward step in a closed position the woman's right thigh may sometimes reach my crouch. Is this normal?

The only way I can think of to avoid this is to make smaller step or to increase the distance between us. Either one would make the dancing look bad.

So, I assumed it is normal/unavoidable but I want to be sure.

p.s. for some reason I cannot select a specific forum

I doubt that your problem has anything to do with the Lady's height, but sounds as though you have taken hold with her too far to your right side, and/or that you are using CBM so strongly on your forward step as to distort the track of the LF on or across the line of your RF (and so stepping in CBMP).

If you have Lady's thigh in your crotch, it may also be a fault in her backstep, in that she has not allowed her toe to slip back for the full extend of your stride (as indicated by your lead), but has shortened her own backstride by lowering to ball of foot early. This will have the effect of preventing any further backward movement, while you are still moving forward, with the inevitable coming together of the bits in between.

Of course, someone would need to see your movement to be certain.

The problem is that the woman is not lowering enough. When I dance with a man who is shorter I bend my knees more and I also bend at the top of my legs, like I'm sitting on a motorcycle, but without my rear end sticking out. The woman should adjust her position if she feels herself coming dangerously close to your crotch. Most social dancers are far too upright.