Why do I always assume he’s cheating even when he’s just busy?

Name: Isha Malhotra

Date of Birth: 21st March 2003

Place of Birth: Indore

Time of Birth: 2:25 PM

So I have been in a relationship for the past two years and when he takes longer to reply, my mind instantly imagines him cheating and talking to someone else or doing anything with some other girl. I check his timestamp even when I have his live online status. I constantly check it every few minutes to see that he is at home and everything and this is exhausting. I want to keep it a long lasting relationship and I feel like my trust issues will get me into a breakup and I don't want that. Is there anything in my chat that could say how could I do this and why it makes me overanalyze love?