Alexis actually doesn't want to go for MC on the secret path, but she appreciates some of MC's actions towards her, and you can interpret that her feelings for him begins to secretly grow, because Erynn points out that they look good together, that MC is the perfect representation of Lexi's type, and that MC is her first kiss.
for now, a seed is planted in her mind, and it grows quickly. it's actually an interesting path because of how she reacts if you dated both.
and yeah, Erynn is the worst when it comes to screwing others for MC.
even though, she is supposed to be a good and nice person who doesn't want to involve and hurt others with her issues.
when you go run with Val and Layla together the first time, you go pick up Layla, and on Alexis' path, it's Alexis that opens the door, and Val clearly sees that MC is dating Alexis. she comments on it. and she still allows MC to hit on her. to her, "just dating" is ok, but it's not ok when it is a "serious relationship". but honestly, what is the difference? only that they officially declares that it is serious. Alexis threw herself half naked at MC and kisses him in public, and is comfortable with him seeing her like that. But Val sees it is more serious on the beach double date ? Why ? they fool around when Lexi tries to get his phone, MC applies sunscreen on her back, they go play in the water and MC walks back with both Lexi and Erynn on his shoulders, that's about it. how is it that different to Val to make it "serious" ?
it's only been 5 weeks. and Lexi expects exclusivity from day one, so it's always been serious to her.
that break up should be epic, for sure.