2 possible reasons for diverging tips.
1. you're too far back in the fore-aft plane.
2. you are not establishing a platform on the new outside ski (you are banking into the turn or pushing the outside ski away from you).
from your pics it looks like you are reasonably balanced in the fore-aft plane, well enough, anyway, that this is probably not the source of the problem. have to actually see you ski to be sure.
it is obvious from the 3rd pic that point 2 is your big issue. balancing over the outside ski. people are often taught to put their "weight on the outside ski". I am not a fan of this way of thinking, because more often than not it results in students pushing that ski away from them rather than them balancing over it. they feel pressure on the outside ski so they assume they have it right.
try thinking about it this way. get up right now, and do this in your living room. try to balance on one foot. notice that, if you are lifting your left foot and your upper body is tipped to the left, it's impossible to balance, you topple over to the left. if you are standing normally, with your upper body centered between your legs (kind of hard to explain this, but imagine an equilateral triangle, with the bottom 2 corners your feet, and the top center point your upper body) and you lift your left foot, you will still topple to the left. Play around to see where you need to be, with your upper body tipped to the right so it is over your right foot to maintain balance on that one leg.
next time you are out, try this standing on a steepish hill, with your skis pointing across the hill. lift the uphill ski. tip your upper body over the downhill ski (laterally, no twisting) so your center of mass is over your base of support (the downhill ski) and you can balance on one foot.
when skiing, if you do not establish this balance over the outside ski early in the turn, you will topple to the inside (you won't fall as your inside foot is on the ground). the outside ski will track straight and you will have no control over it. diverging tips. the end of the turn will be skidded and uncontrolled.
so, the fix. the suggestion of lifting the tail of the inside ski is a good one. leave the tip on the ground so you can maintain your fore-aft balance and avoid throwing yourself into the back seat. lift as early in the turn as you can, thereby keeping the outside ski underneath your body as opposed to pushing it away from you. you will feel a strong, stable platform from which you can increase the edge angle without the ski sliding out from underneath you. do this at slow speed so you cannot "cheat" by using your speed to keep you upright.
this is a lengthy explanation, I hope it makes sense! in summary: instead of banking into the turn or pushing the outside ski away from your body, balance OVER the outside ski as early as possible in the turn, and continue the turn from that strong platform.
enjoy!