Most Helpful Girl
I’d say whether he’s cheating or not, you still have a guy who maybe may not have interests elsewhere. The only way to be able 100% sure is to confront him, and have him text her while you’re together. See how the chemistry is from her, and if she’s flirty you know. If it’s kind of dry, eventually she might say something like “you seem different...” (because he’s not flirting or being the normal him.
Another way would be to perform a surprise dominatrix session with him. Then he couldn’t leave you even if he tried. Dress up as sexy as you can, tie him up and tease him as long as possible.
He’d go to work and about his daily life, not being able to get you out of his head.
Grab him by the balls and assert yourself as the alpha woman in his life
Most Helpful Guy
If he blocked her for you & you don't think they're still communicating behind your back I say count it as a win & move on. If you don't think there's anything going on between them it's not worth dwelling on. I can't see myself cutting any of my female friends out of my life for a girlfriend. Even the ones I've slept with before. It's a trust thing. I believe my girl should trust me enough to know that she's the only one I'm sleeping with & I can have platonic friends & vice versa. I also would introduce you to any & every woman that's important to me. Especially after 3 years. I think it's no big deal based on the info you've provided