Men will say whatever they have to on dating sites to get a woman interested. They're likely to get more replies if they say they're "romantic, want weekends away etc" than if they're honest and say "I have 4 nights a month free and I'd like a guaranteed shag on all of them".
Take from this story what you will...
A friend and I were both single. I was looking for a FWB and she was looking for something long term. We met in a coffee shop and started talking about the guys we were current chatting to online. I made a joke about a guy who was the spit of some celeb. She nearly choked on her carrot cake. She was also chatting to him. Fair enough you may say, no one is exclusive when they're just chatting, however, we weren't using the same sites. She was chatting to him on Tinder and he was giving her a load of flannel about how he was looking for something long term, wanted to have kids etc and I was chatting to him on Fabswingers where he was telling me he was just looking for a FWB, was crap at relationships and didn't want the hassle that came with them after being burned too many times.
Of course we had some fun over a couple of cups of coffee both messaging him at the same time. His phone must have been 🔥 trying to keep 2 conversations going at the same time... He eventually clicked what was happening when we started asking him the same questions. The cheeky sod then asked if we would consider a threesome!
Anyway, moral of the story is (most/some) men will do/say whatever it takes to get their leg over. It's really not you, it's them. If he's back on the apps, he enjoys the thrill of the chase and you're better off out of that situation. At least he ended things with you before moving on.
Don't give up, but don't give yourself so easily. Hold something back. I don't mean sexually, I mean mentally and emotionally. Don't give too much too soon to the next one. Make them work for your attention and your time. Don't be too available. Men value scarcity. He wasn't the one for you, but you'll be the one for someone, and when that happens, you'll have no doubt about his intentions or feelings.