Girlfriend never discloses she has a bf to men hitting on her online/text/person

[Guest Influx4567]

She just told me over the weekend,, that her cousin had a party and invited all his friends. One of his freinds got her business card. He text the next day to pretend to talk about business, she knew he trying to hit on her.. And instead of saying she had bf, she said it s not right that he's hitting on her because it's her cousin. Which I would imagine only brings a man hope, like "oh i could have had her but her cousin would beat me up"....not surre why she could just say "i have bf", she claimed to block his number.

 

Also on her social media account, there is no mention of me, pics of me, etc...However she is still clingy, always wanting to hang out all the time. I'm always there for her, lend her money....she talks about marriage. All this leaves me confused. I was her first and she claims she wants to be her last. She's 21, I'm 29. We dated for 3 years, but this 21st bday weekend and her party ways would only leave me with gray hairs and age like milk. Should I just break it off. I've been wanting too, since she has a bad attitude that I'm a homebody.