I'm glad you're enjoying the story! Your question is valid, and I very much understand how you feel about this aspect. I'm going to try and hide a vague answer because I know this is important to some people. However, while vague, I feel it may be a sort of spoiler, so read at your own discretion.
While I cannot reveal specifics, I can assure you that I've taken into account the different lifespans and the implications they have for relationships in the story. I cannot say much else, but only please try not to worry about this element!