Please use this thread going forward: [HSY] Teen who graduated early still get popup about prom | EA Forums - 11945324
Several subcategories here:
Teens that graduate early have their love interests become resentful for no prom invite (has nothing to do with being in college, the resentment occurs if the focus sim is in college or not.)
Teens who drop out have their love interests become resentful for no prom invite.
Teens with young adult or older love interests have those love interests become resentful for no prom invite.
In all these cases, the teen is prompted to go to prom, but there were no interactions available to invite the love interest to prom. The resentment triggers whether or not the teen goes to prom. One one case, however, I was able to avoid it when my graduated early sim went to prom, found her love interest wasn't there, and invited him to the lot. In my most recent case, two teen sims who never went to high school (dropped out at the start of the save) and were lovers went to prom together, and both got the no prom invite sentiment as soon as they arrived.
There are (at least) two edge cases that got overlooked: the active household teen must be in high school for the love interest to have the resentment added if not invited (the teen shouldn't even have the option to go to prom if not enrolled, just as there is no option to go to prom if they aged up before prom started) and either the teen's love interest must be a teen (so able to be invited to and go to prom) or the ability to invite to prom must be available on all love interests as well as all teens (with a high likelihood of having the invite turned down.) In the latter case, even if not invited the older love interest shouldn't get resentful as they've moved beyond all things high school.
