I think that must be the only MC who actually has a real reason for mistrust and doubt. Every time he starts to believe in someone, the other girls shatter his trust.
I kinda liked Shield Hero for this reason too, Naofumi already had trust issues and was given a lot of good reasons to double down on them. It's not exactly a shining star amongst the already low bar of isekai, but I liked that it actually gave a believable justifcation for the whole "my closest female companion is a slave" thing. Maybe not a
good justification, but definitely a believable one. Dude's ability to trust people was so shot that he felt there was
nobody he could trust if they weren't a slave, and after getting to know him Rafu opted in to staying a slave to help soothe his mind, to show him that he could trust her and to show that she trusted him enough to not abuse it.
The whole willing slave thing is still a pretty fucked up situation, but it's an understandable fucked up situation that resulted from a broken guy with a fucked up mentality.
Shame that every other isekai to come after has to have the obligatory girl who loves protag for no good reason unconditionally so much to the point that she literally begs to be his slave forever and cries if he tries to free her so they can just be normal friends/lovers/spouses/whatever.
That was a big yapping tangent but basically yeah I'm also happy to see a guy who actually has a very good reason to be paranoid and it makes the romance interesting instead of making it feel like he's just being dense.
I really like how his relationship with his brother seems pretty normal too, he's not needlesly antagonistic, just a chill older brother who happens to be extremely handsome and popular with every female in a 50 mile radius.