Guy's Behavior

Is he trying to send me subliminal messages?

So I was talking to my boyfriend earlier asking if he was happy or not with me because he's constantly flirting with other girls on social networks and forming relationships with them online while he's living with me. He said something along these lines ''It's not like I'm in love with someone else and not you, it's not like I want to leave you'' And then I had to ask myself wtf is he talking about? I never once said anything about him being in love with anyone else or leaving me I just wanted to know if he's unhappy with me and wanted to move on. From his actions he's not happy with me because if he was why is he still interested in other girls? It doesn't help that he's a few years younger than me either. I feel like an idiot. Anyway what do you think?
Is he trying to send me subliminal messages?
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