parenthood randomly glitches out after lovestruck update

cyberism  For comparison's sake, please test with a different household in the same save, one with a teenager.  You don't need to save your progress after switching households.

If that other household has the same issue, try a new save, again as a test.  You can also save your existing household to your in-game library and place them in a new save to see whether the problem sticks to the sims.

I'm not saying your save is broken beyond repair, only that it's useful to narrow down the scope of the problem.