The only thing that gets blocked from Ivy/Lena is the sex scene after the birthday party. You need to have 7 or above RP for Ivy to initiate her invitation to stay at her place. Other than that just some minor dialogue changes but they still consider each other as friends and admit that they are drifting apart.
For setting up Louise/Lena. You don't need to be on bad terms with Ivy.
- Select "Does that mean I will be seeing even less of you?". During dinner.
- You can either tell Louise about Jeremy or stall till Ivy plays her truth/dare game after the party.
- Be sure to attend the truth/dare game after the party.
- You need to have 8 to 10 RPs with Louise.
- Accept her 2nd kiss and you are done setting up Lena/Louise's path. The first kiss is always auto-rejected.