Haven't tried 21.3 yet. But as of 20.5, the last option that will kick you from Lover to Happy is if you refuse to visit Liz's Mom. This will significantly drops her affection from 100% to 90%. If you accept visiting her Mom, the rest of the options are still Lover safe, even on those when you decided not to visit Liz in the office, declined joining her shopping and clubbing, or not checking her in the club bathroom. And of course, the result of these negligence will be Matt's event on Liz. But even so, you are still on Lover path.
As mentioned by others, we will see if these will change in 22.0