Should I dump my girlfriend of 5 years and move on with my life?

Hi folks,

I found this forum yesterday and today I decided to share my relationship problem with you. Perhaps you can help/guide me.

Background:

We have been together for 5 years. During THAT time, we've had 3-4 minor break-offs. During that time, she has always gotten a rebound guy for her and it has never worked out for her. Every time I go NC and after few weeks, she's back saying that she only wants me. Now things have settled a bit, but I'm still not happy with the relationship.

She is 22, I'm 24

Story:

I'm not going into too much detail, but the problem is that she constantly looks for validation from OTHER men and I'm insecure about it. She chats with other guys, flirts with them, sends snaps (some teenage app) (constantly on her iPhone), she meets some of them when I'm at work (she is not working, I'm giving her money) etc.

I go insecure when she is talking with other guys. I know I shouldn't, but I still do it.

When I told her that I'm not accepting her "male friends" then she always goes nonchalance and tells me that they are only friends etc. The thing is, she has only 2-3 female friend and around 10 male friends. I'm not sure if we are on the SAME PAGE of relationship. She wants to get engaged, but I'm not sure what to do.

I don't want to get engaged just so that he can continue chatting with other boys etc.

I'm ready to dump her since I'm feeling this is not going to work out well. She has not been able to change although I've been giving her literally everything she wants. '

However, before I break up wit her - I want to fully overcome her. So if we breakup, I won't have any bad feelings eventhough she might get an instant rebound.

What should I do? How can I be nonchalance about his mobile phone addiction and constant validation looking? I'm tired of watching every her day/night on the couch chatting with other guys. It drives me crazy and I'm feeling that I'm pointless guy in her life.

How can I break the ice and become a dominant, more non-chalance person in this relationship? Should I try or dump her asap?

Sorry for my bad english, but I really had to share this.