I can't speak for all guys but thinking of marriage before a first date is not something that is in the forefront of people's minds when first meeting a person. It is not lying to not mention marriage upfront.

I am sure there is a lot about you that you didn't mention, is that lying? No! Saying something like "looking for a serious relationship" is a lot less scary, even for guys that want to marry. A first date should be the goal and marriage is a long way past that and really shouldn't even be in the conversation. Maybe after a month or two broaching those really serious topics will go over better. People may not want to get married today, but will sometime down the road. I just don't think marriage is a good screening test for a first date. I could be wrong. I am probably the last person that should have got into this conversation.

There are a lot of reasons why a person won't message back. Maybe they didn't like that you are into cosplay or your music(I like a lot of the same music and it sometimes intimidates people-some people will assume I am aggressive or a stoner, neither of which is true), maybe they are currently seeing a few people and are busy or maybe work got too busy temporarily. You are not ugly. It is possible that some were not attracted to you. There have been women I have thought were very pretty and my friends of either gender thought they were not.