4. Pay close attention to how your partner treats your kid.
Trent is astoundingly immature and passive-aggressive in his relationship with Duncan. He constantly accuses Duncan of not pulling his weight chores-wise, he makes him wear a life jacket when everyone else is okay with him not doing so, and generally embarrasses him, implying that Duncan is immature. He's trying to assert his place as the head of the household and Pam should be very careful about letting him take on that role. Instead, she lets things slide too much.
5. Make your partner's kid feel welcome and loved.
Pam is much more sensitive to Trent's daughter Steph (Zoe Levin) than Trent is to Duncan. When she finds out that Steph and her boyfriend broke up, she sincerely says "I'm sorry," but tries not to invade the teenager's privacy. It's a bonding moment, and we don't see any bonding between Trent and Duncan. The only time Trent talks to Duncan is when he criticizes him, so it's no wonder than Duncan feels no compassion for Trent when he's faced with a tough decision. If you want to show your partner a glimpse of what your life together would be like permanently, you should be good to their entire family. Your relationship is not just about you two.
6. Don't let a new partner "take over."
When Duncan appeals to his mom about Trent's criticism, she tries to smooth things over, saying Trent is just trying to help. It makes Duncan feel like his mom won't stand up for him. She shouldn't let her boyfriend take over as a parent. As much as she seems to want Trent in that permanent parenting role, that's something that should be established over time. Also, it's clear that Duncan is grasping for a father figure, but not just anyone can take on that role: It has to be someone the child trusts.
Image courtesy of Fox Searchlight Pictures