Here's what I think: since you mentioned Matt banged Liz after the Student presentation, means you might have chosen a Happy option on the dialogues before the presentation.
Going back, did you manage to avoid Liz to stay in the camping event? If you avoided that, then the wrong option might have selected in any of the dialogues after the camping trip.
Try to go back to the camping event scenes if you have any saves on that. Then, make sure you select the SAFE choices by focusing in these things below:
SHOPPING. Safest choice is you go shopping with Liz instead. But if you decided Liz shopping with Sam instead, make sure to select the choice that you do not like other guys ogling Liz.
CLUBBING (if Liz shopped with Sam). After shopping, Sam will invite Liz to the club in the evening. Do not ask Liz to wear something daring, just tell her have fun with Sam. After that, do not encourage Liz to drink more, tell her they have enough.
POINTERS FOR THE PRESENTATION. Do not ask her to "show some skin", just select salary and benefits.
If you have done everything above correctly, you will be staying safe in the LOVER path. You will then see the scene where Matt will try his "soft strategy" on Liz by kissing her gently with the purpose of making her heart question things. The scene is still uncomfortable if you are a pro-MC, but at least you avoided Matt banging Liz.