You care, you care enough to relieve yourself by asking a question about it. If you don't care, why does it matter whether he's lying or not ? Live your life & let him say whatever he wants. If it's bothering, tell him to stop talking about it. But nope. It taken your attention somehow, & it made your mind busy by any reason. Otherwise you wouldn't ask this question.
Now, it could be a lie, it could be a truth, doesn't really matter, but since you care, legally it's fine cause the guy is 18 & he's in legal age & he can date anyone he wants. & the girl's age is also completely out of the discussion. A complete grown girl.however age never determined the "Maturity" I can make an example of grown people that have the most false information & the most childish behavior. & this relation or claim of relation is not that odd. I've seen plenty of examples that 18-20 years old, dating & even marrying 24-30 years old. Love is love. Love doesn't care about numbers such as age, height or weight. & if it be even a simple dating between these two. Yet, this is their will, & they can do whatever they want. It's not something out of sense or odd. It's normal & it's their own business.
