@Livelaughlove196,
I have never heard of a promise ring before. It doesn't seem to mean anything other than a monogamous relationship (which is the norm after 5 months of dating).
Isn't this something you should talk about with your partner?
If he is asking you to commit to marriage, then I would say 5 months is probably too soon. But if this were the case, he would be giving you an engagement ring instead of a promise ring.
If the promise ring is a way for him to let you know he is really serious about the relationship and that you are special to him, then it is appropriate (if the relationship is at that point and his feelings are sincere). It would nice if you felt the same way, but it seems like you don't (which is perfectly ok). Either way you should be open with him and discuss your feelings directly.
The key to any relationship is communication. The only people who can decide what a "promise ring" means is you and your partner. And you two are the only people who can decide whether this matches the level of commitment of your relationship.
After all, we are just an anonymous voices on the internet. Talk to your partner.