unhappy in a healthy relationship ?

so i’ve been with my boyfriend for 3 years and overall we’re pretty happy. we don’t fight often and when we do we talk it out and that’s the end of it. but for some reason i feel like… somethings missing. like im either scared he’s cheating or he doesn’t appreciate me or he misses his ex or

literally all of the above. and i dont know why. he can be a bit lousy at times but i feel like anybody in a long term relationship can get lousy sometimes u know?? like i feel like im always expecting perfection and constant affection and when he doesn’t show it i just start to overthink so much. lately i’ve been getting a feeling that he might be cheating on me and like the signs aren’t even there, he’s always texting me throughout the day and he always calls me at the end of his day or if we’re both home and not doing anything. but i’ve just been getting the feeling that he might be doing something that’s gonna hurt me and it’s making feel so miserable. my friends who are also friends with him tell me that from the way he is with me, it’s unlikely that he would even consider cheating but i dont know :/// it also could just be the fact that i recently caught my dad cheating on my stepmom so maybe it’s just triggering my trust issues??? i dont know. but without the cheating thoughts i still feel kinda bummed in this relationship. i feel like sometimes he can be a bit selfish when it comes to his feelings and multiple times recently i’ve been having to put aside my feelings to cater to his. and i’ve told him and he said he’s sorry he’s just been unbelievably stressed but i still feel kinda crappy:/ like he takes care of me but i still feel like i need more. i don’t know if i’m being selfish or just destructive plz be honest :x