Oh, I'm a huge introvert and have no friends (male or female), in-person, that I see or call regularly. I'm friendly enough to neighbors and coworkers to meet social expectations but that's about
it. So I'd not call a female friend a valentine jokingly or not lol. My best friend is my wife, we have all of the same interests and hobbies and we do everything together.
Reading guys is tough. Whosit might've been trying to be funny, cheer you up, seeking emotional attachment, or being a sleezeball *shrug* who knows. From what you describe regarding the muddy ambiguity, I'd say it's safe to say it's equally muddy on his side as well. Emotions are funny things, not always clear. In the end I think you're right, we're all human not purely evil or good including whosit.
After being married a long time the initial excitement of initial dating is gone between spouses, become more like friends/roommates. Maybe some married guys flirt for egos (i still need to know, i still got it, am attractive or whatever), for boredom in a marriage, lack of romantic interest from their partner *shrug*. Certainly having kids adds another layer of separation between partners, less time for bonding with each other when the bulk of time is caring for kids. I see obviously married coworkers flirt with each other. Likely mostly harmless with no intent of cheating I think for most of it. Maybe it's a quick pick me up, that someone notices you dressed nicely or are in a good mood. If somebody says something nice to you, you generally feel better afterwards. Most hardly look your way, nevermind notice a change or take interest lol. Reading others intentions is often just guesswork. Might be right or might be wrong.
A parakeet might be fun. My parrotlet is mostly cage-free, flying around the house when someone's home. I hold him and pet him. He's super clingy and doesn't stray far, always keeping an eye, or on a shoulder. Really cute little guy. Fish are neat too, but less interactive.
It might be a little scary to volunteer, to date (when you're ready), etc. However, to change things for the better you're going to have to step outside your comfort zone a bit. Not easy for introverts but necessary