My question to those who support this love interest angle. How would it bear any relevancy to the plot?
I don't even support it and I can answer that. It depends on what the plot is. The love interest could be involved with the evil team (either helping you or a member of the team that switches sides.) You going for the gyms could be explained as trying to impress your love interest, which would explain why you're older.
I'm not saying these are good ideas, but the way you said it made it sound like it's completely impossible for it relevant at all. So yeah...