Is my gay friend really gay?

One of my coworkers is gay (he’s a guy I’m a girl) and we’ve become close over the past few months. He never gives me weird vibes in person but sometimes he’d text me drunk and say stuff that’d surprise me. One time we were texting and I sent him a picture of me in my new clothes (they were kinda revealing) and he told me I was hot and said ‘you know I’m actually bi not gay but I never tell anyone’. I knew he was drunk so I cut the conversation but I asked him a couple days later if he was actually bi and he avoided answering the question. He’s always the first person to know when I take any of my posts down on Instagram and I asked him a couple times why he’s stalking me like that and he never explained. One time I sent him a picture of my skirt but I put a sticker on my butt because it was showing a little and he told me to remove it and send the full picture. He also started saying that he loves me, not in person just in text. I know he could mean it in a friendly way but I can’t tell anymore. I have a boyfriend so I feel like even if he was bi maybe he’s just trying to be respectful? At the same time why avoid answering my questions about it?