unwanted conclusion

Is it okay to be slightly jealous if your boyfriend is talking to a girl almost everyday. It wouldn't be a problem if the girl was a old good regular friend but this girl is new and he's been talkin to her almost everyday for a good 4 months now. I'm normally not the jealous type but for some reason this situation is really bothering me.

update for more information:

I'm 19 years old and I graduated in June. My boyfriend did the same and is 18 atm. Me and him recently just got back together after we broke up for many reasons.(if you want more info on that just lmk in the comments) The girl he talks to is about 17 I think🤔 and she used to date one of his friends but even then he never mentioned her and he never even talked to her. He told me the other day that they started talking bc one of his other friends wanted him to hit her up and ask if she wanted to smash his friend. Apparently they been talkin ever since but it was weird bc her name never popped up in his messages until recently,🤔 so that means he kept on deleting the conversation. Now he keeps the conversations bc I caught him texting her before he even told me about her. I could be just over thinking it but he even started acting strange about his phone and he never did that before. He doesn't even leave his phone around me anymore. I respect ppls privacy so I wouldn't go through his phone even though he went through my phone one day. It's just that now I'm so paranoid and I don't want to lose him. I don't want his attention on anyone else. I want him to come to me if he wants to talk or to show a joke or something and tell me how he feels if he's having a bad day, not some other girl. Is that bad of me? All these feelings are so strange to me bc I've never worried or got jealous. 😂😂 I even went out my way and added the girl on snap and post pics of me and my boyfriend and posted things about girls talking to other girl's boyfriends smh only bc I wasnt sure if she even knew he had a gf. Now I feel stupid bc I normally dont act like this😅I've always gave trust in my relationships. Ik some think "you can either trust your significant other or don't" but it just seems more than that, more complicated. smh I'm young and I still got alot to learn but I'm coming to this unwanted conclusion.

this is what I posted on snap😂