Y’all, first off no romantic connections have been formed at all yet, both seniors clearly want only see her as a friend now. And secondly, mc has gone back in time so mentally she is an adult. The school setting is what created a bridge for them to meet so later on in the story when she’s physically an adult again it won’t be strange for them to help her meet her goals. Also a 6 year age gap really isn’t that deep, the only thing weird about seniors liking freshman is the mental gap which clearly isn’t the case here.