His close girlfriend made us quarrel

Wherever you go, tell her. Do you really have feelings for your best friend?

I am 24 years old, he is 30 years old, know each other nearly a year. I am sociable, a bit childish; He is quiet, sometimes childish. We had a little argument, but a few months ago, we argued because of his best friend.

He and her have known each other for 10 years, met again in 2017 and texted to ask for drinks and talk. He told me about this sister, saying the two were just friends, so I agreed to know him. After half a year I saw her texting more with him, every 2 days to text, he also responded. She texted that he answered right away, and I took a minute or so before he wrote back, he told me to work, so he could not respond. Wherever you go, tell her. On business trips outside of Hanoi, he also asked if she needed to send anything, even this he remembered while she spoke more than a year ago.

He and she went out with friends a few times when he first met me. I'm jealous but he doesn't care. I'm angry, he said he would talk to her but then did not say. Then I forced him to post us on social networks when I saw her hinting that she had feelings for him. I haven't texted in two months, should I be jealous about this? Does he really have feelings for that girl? Hope you guys can give me suggestions to grow up.