There is a small thing about that though. Even if you never choose creampie options with Nikki, she still throws up. We all assume it's because she is pregnant but we cannot be sure. Though, maybe event's reason differ later. Like if you chose she throws up because she is pregnant, if not alcohol and heat made her sick.
I am also like that, probably a little bit stronger than most because irl experiences but I do understand Alexis' POV. She was not trying to mess with MC or Erynn, she was scared. In her love path, there are lots of hints that she have a crush on MC since their childhood. He is her type when grown up also. Erynn told over and over again in ASP. First time she realised who was MC, MC literally blamed Ethan and Alexis for everything happened. She was into him before she realised who he was also. What should have she said? Oh yeah, that was me. That was the reason her turmoil within, each time she tried to stay away from MC but she was too deep in love with him. She could not talk with MC because she was scared to lose him, she could not talk with Erynn because she was scared losing their friendship. Also the day, Erynn and MC figured it out she was going to talk about it with Erynn and most likely with MC afterwards.
So I don't think she was dishonest, she was scared and needed time to figure out things. It blew up before she acted, so I do understand her.