In Fallout 4, you can enter a relationship with as many companions as you like without the fear of repercussions. Before you can enter a relationship with anyone, you have to make sure your affinity level with that companion has reached the maximum level. You can check out our handy guide here on how to raise your relationship with every companion in the game. Each time your affinity level reaches the next threshold, you’ll be able to have a conversation with your companion. He or she will start repeating the same line of dialogue over and over until you talk to them. You’ll then have to pick the ‘romantic’ or ‘flirtatious’ dialogue option to get the love train chugging along.
However, do note that successfully pulling off all of the romantic dialogue options requires a little bit of Charisma and Luck, so it’ll be wise to have at least a few points invested in both of those categories. Even if your Charisma and Luck levels aren’t that high, you can always quicksave and load again until you successfully get past the speech check.
Piper can be found outside Diamond City. Upon reaching maximum affinity with her, she’ll give you the Gift of Gab perk.
Preston can be found at the Museum of Freedom in Concord. Upon reaching maximum affinity with him, he’ll give you the United We Stand perk.
Paladin Danse can be found at the Cambridge Police Station. Upon reaching maximum affinity with him, he’ll give you the Know Your Enemy perk.
Cait can be found at Combat Zone. Upon reaching maximum affinity with her, she’ll give you the Trigger Rush perk.
Deacon can be found at the Old North Church. Upon reaching maximum affinity with him, he’ll give you the Cloak and Dagger perk.
Macready can be found at The Third Rail in Goodneighbor. Upon reaching maximum affinity with him, he’ll give you the Killshot perk.
Hancock can be found in Goodneighbor. Upon reaching maximum affinity with him, he’ll give you the Isodoped perk.