Is it ok for gf to chat with other guys online?

[Gary]

My gf and I have been talking for 4.5 years we have been together for 2. We have even talked about getting married. I looked at her social media accounts and all of her friends are guys for the most part. Before we dated she use to send nude pictures to guys and use chat rooms. She says she has stopped. There is no proof that she lied. Most of the conversations are pretty basic, but with one of the guys she has inside jokes, and sent him a funny meme saying this made me think about you. She didn't use to have Facebook because she got rid of it but she deactivated it and didn't tell me. It bothers me bc my ego of course. It also bothers me because most are complete strangers who only add her bc she's cute. I just think at this point in our relationship she shouldn't be chatting with random guys. She also snap chats a lot of guys. Most of the guys on snap chat she knows though.

[Paul]

If she has been talking to you for 4 1/2 years and been together for 2, there is a time and day that a certain behavior from before must change, when should it have to change? The fact that the 2 of you know each other for quite a while, she's supposed to be more respectful for you than what she's showing now.
Gary, Don't let her step on you, you're the man in the home, and you must have the respect of her and the other way around also. It's definitely time to make that happen, if not you're kicking the can down the road until it'll turn more serious.
Act NOW Gary,