Is it wrong that I don't want my boyfriend to use my lighter?
Why won't you let him?
He lost my other one.
It's okay to not give your lighter to your boyfriend if it is a pattern that he loses it. However, you can share it with him and ensure he gives it right back.
It's his fault for losing it and he's stupid for buying one that looks like my other one.
Talk to your partner about how you feel when it comes to sharing your lighter. He might not be aware that you are upset over a lighter that he lost.