Relationship between Keyleth and Vax'ildan

During the near-death experience he experienced of his life flashing before his eyes, Vax'ildan thought of Keyleth as being "beautiful, walking under the trees". Vax later revealed, after almost dying again, that he was in love with her. This greatly flustered Keyleth, and she admitted to having some feelings for him as well, but she revealed that she was afraid of pursuing the relationship. Over time, she was slowly becoming more open to their growing bond.

After Vex'ahlia was killed and resurrected during their search for the Vestiges of the Divergence, Keyleth later explained that she was scared of losing Vax and, while she thought she loved him, she felt as if she was too terrified to allow herself to because of her fear of outliving and losing everyone once she completes her Aramente.

However, after saying their farewells to Tiberius after they buried him in the ruins of Draconia, and after having been given encouragement by her father, Vex, and Pike on separate occasions, she finally decided to talk to Vax again, telling him that after having talked to Pike, she realized that her fear was purely based on an unwritten future and they they ultimately had "nothing to lose". Having said that, she finally confessed that she loved him and had been for a long time, apologizing for taking so long to say it. Vax then admitted again that he loved her as well.

Vex'ahlia's Reactions to Keyleth and Vax'ildan's Relationship
Vax didn't talk to his sister about his love for Keyleth, which caused some tension between them. Vex also, for the most part, seemed to resent their potential relationship initially and made a point of disturbing their private moments, and she teasingly reminded them that Kashaw kissed Keyleth when they returned to Vasselheim. When Kashaw returned to Keyleth's life, however, Vex wasn't as resentful as expected and instead tried to encourage the druid to make her move with Vax, which she did when she openly kissed him after Grog's test of character against Earthbreaker Groon. Vex continued adjusting to the reality of her brother's feelings, and after the party survived the slaughter of Umbrasyl, she asked Vax what's going on with him and Keyleth, but Vax refused to answer. Vex then asked how Keyleth feels about him, and Vax replied, "Ask her." So, Vex promptly asked Keyleth, who reluctantly admitted to having feelings for Vax and asked if Vex would hate her for that. Vex, after her death and resurrection, however, was no longer resentful and encouraged the druid to just be happy and not live in fear. Since then, she still teases her brother about their relationship, but she also hasn't shown any further resentment, admitting to him that it makes her happy to see him happy.