Even if you don't get an std, can frequent sex, kissing, all of that actually damage the body's own immune system, making it much more prone to getting other infections such as colds?

I often questioned this, because having sex with another person or having multiple partners does expose you to the countless germs, bacteria, etc, that that person carries, so therefore won't that still somehow affect your immune system, even if it's not a major/minor std?