I am completely lost

It's a powerful feeling when you figure out you don't need anyone else to help you survive.

...Simple answer OP: The grass ain't greener man. If you have a good girl and a stable relationship, and you want to give that up thats fine, just don't think you're giving it up for anything thats going to make you more happy or more content. Both of you guys will have your emotional backlash moments if this continues. Not to mention you don't even know the girl.

Sounds totally unnecessary, IMHO.

Talk to your girlfriend about a threesome. That's what I do when I get bored. Most of the time they'll be cool about it.

If that doesn't work, experiment for a few weeks with an open relationship. There doesn't have to be an "end it all" scenario if you set aside jealousy and neediness. You can still keep a great girl in your life.

Also, I think 100% happiness with a person is complete bullshit. Every girl is going to have a flaw or two that makes you think. You just have to decide if all her positives outweigh the flaws.

If a girl I cared about was really into trying that, I might.

I'm not interested in serious relationships filled with drama and "talks". That should be a small percentage of the time only.

Relationships should be fun and mostly easy, with strong levels of attraction and exploring.

OK guys so I massively fucked up here, I was thinking with my dick and not my head.

It's been almost 2months. We lived together and for the first 4/5 weeks I managed to stay at a friends while they were away. Although ex and I still saw each other at weekends. Last 3/4 weeks I've been back at our shared apartment while I find somewhere else to live. During this time I've acted more like a friend rather than relationship (although we have had sex several times). I told her a few days ago that I did want the relationship, was sorry for hurting her and handled the whole situation incorrectly.

She said she didn't know if she wanted it anymore as all she can see when she looks at me is the hurt that I caused her and she doesn't trust that something like this wouldn't happen again.
She stayed at her parents the last couple of days but we had a conversation this morning where I apologised (sincerely, strong, acknowledged my mistake and laid out future behaviour that ensured it wouldn't happen again). We had sex. I reiterated the apology post.

All the way through we've said we love each other and she said she still does. She said she wants to be just friends now "if I can handle that" and see if it develops back into a relationship although I'm not to treat it as anymore than friends. She's happy to have sex though. Also, she's been on a couple of dates with another guy.
I move out tomorrow.

Is there a way to save this? What would you advise?

We have Latin & Ballroom lessons on Tuesdays, do I still invite her or no?