Am I the only one who has a hard time trusting people who don't have friends of the same sex?

I think it rubs you the wrong way because that would be extremely unusual. And unusual things rub people the wrong way, so it is only natural.

It really depends on the person, some people are naturally better at being friends with certain genders / sexes. I have quite a few female friends because they usually come to me for advice, but I do have guy friends as well. I suppose you can look at only having opposite sex / gender friends as they are trying to get with them but that may not actually be the case.

My best friends are girls (though we haven't been talking) but I find guys approach me more than girls do so it's easier to make friends with someone who seems to want to be friends. I don't seek a lot of people out though so maybe if I made more of an effort I may have more girl friends

I try not to judge people since I'm sure they all have their reasons or circumstances. I have a friend who was raised by a single mother and has two older sisters, he usually only feels comfortable around his female friends since that's what he's used to. If you're talking about the online scene, (such as this site) then I could see how you might find the people with only female friends as a male or vice versa to be aloof or suspicious in their motives. Of course, it's to be expected since people are perhaps more interested in the opposite gender, if you have a ton of male friends in real life then you might want a fresh breath, and want to befriend some people of the opposite gender and take advantage of the anonymity to alleviate the usual awkwardness. I don't really actively search for friends on here but I've noticed that women are more willing to talk to men and vice versa, most of my friend requests I've received have been from the female gender. This may just be me but people of the same gender on here seem to be indifferent towards each other and would rather friend the opposite, most of the guys that I have gotten friend requests from on here (which is rare) never really seem interested in talking. This also isn't a full-blown site for finding friends; it was started as a dating site if I'm not mistaken, so there are still remnants which will cause it to appear this way.

Doesn't really matter - If you feel uncomfortable with a person's life choices just go find another, they have no obligation to change their lifestyle to fit yours, and the same can be said again in reverse. There is nothing anybody can do to show that you can trust them, It's not tangent - just like love, you can't hold anything in your hand that will prove that they love or that you can trust them, Since it's not tangent, Come to terms with it and accept the fact that if they wanna be free and do whatever, they will. Now the greatest gift you can give to someone is the freedom to be themselves, and if you treat your other well - then you don't have to worry about them cheating, and even if they end up cheating - then that just means you no longer have to worry about them. Seek nothing outside of yourself, Not love, nor purpose or fulfillment. People should be seen as an addition to happiness; not the cause of it - If someone betrays you, Then just walk away without a second glance.

I do get uncomfortable at first. Especially if you just started your relationship and realize your bf has a whole bunch of female friends. But if you do trust him, then there is no problem. Though getting to trust eachother is a whole different story. Personally I have a lot of guy friends, cause video games lol. But my female friends are the closest ones to me and I know they have my back. Cause they aren't gamers lol