Megan Fox and Machine Gun Kelly have a lot of “trust issues”. The 37-year-old actress recently revealed she and the 33-year-old musician have called off their engagement but did not confirm if they have ended their complicated relationship. A source told PEOPLE: “The intensity is still there nearly four years into their relationship, but that’s not necessarily healthy. There are still a ton of trust issues between them and it’s very toxic. They can’t stay away from each other and there’s a lot of history there, but they also don’t know how to be in a healthy relationship. They’ll be totally fi…