@Mischa90,
Maybe stop suspecting every little thing and recognize that it is actually good advice to spend time with other people. Plus, people get busy. It's a fact of work, school, or anything else which he or anyone else does. Stop taking that personally, as you have no basis for leaping to any conclusion other than,
he's busy.
Also --
Please do not give anyone this much power over your happiness. Cultivate other interests and, yes, that means friendships. You know, people to have coffee with or go to the gym together or the movies or just hang out on the porch and drink wine.
If it turns out he is cheating, then you will have friends to support you when you drop him like a bad habit. And if he's not, then you will have friends to cheer on your relationship, and you will not have resorted to snooping or trying to hack into his phone. You will have established that you trust him (
because if you don't, then leave now, because without trust you have nothing).
Right now, even though your post is, what, less than 50 words long (something like that), you come across as needy and overly clingy. Step back and have a life outside of him so that if he does leave your world will stay strong and intact.