Why did he say we're not together after 4 months?

What does it mean if a guy says I'm not his girlfriend & we're not officially together yet after texting, calling, regularly dating, introducing me to his friends, buying me stuff & having sex for 4 months? We're 20. In an argument I referred to myself as his girlfriend, he corrected me. Sex happened 2 times (I was a virgin & he knew it). He was like 'even if u were my wife there'll be trips where I go only with friends'. Mixed signals much? What? He called me wifey in the beginning. Said he'd be open to a 3some... Apologized & never brought it up again after I got mad. He said 'we'll be in a relationship' & that he deleted the dating app. I took it as us being exclusive. He said he'd been w many girls but with me it was his 1st time having sex.. He was like 'I never felt so good with anyone'.

We had disagreements. He often travelled without me. I suspected he was gay but he said he was straight. I didn't want him to go on a 2 week annual trip w his friends to the seaside. He said there'd be a club & drinking involved. I found it hard to trust him after that 3way bs. He called me controlling. His reasons for not calling me his girlfriend were that I didn't trust him, we didn't have the official talk & that we weren't close enough to be official, weren't texting & calling enough, were seeing each other once a week or less (untrue.. it was 2-3 times a week). We were actually texting often. I was the one arriving to him.. He said a girlfriend wouldn't make pretences & would ask if he was ok instead. He said it was too soon for love & that he needed time after I said if he loved me he'd take me on that holiday. I ignored him for 2 weeks & unfriended as I was hurt. Then I gave an ultimatum. He said 'after all of this I don't see the prospect of a serious relationship'.

Did he want sth casual or serious but changed his mind? Did I turn him off bc I was upset he was travelling without me often? Is that a reason not to call me his girlfriend? Now he's seeing someone else.

Why did he say we're not together after 4 months?
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