Socialising norms

One thing I notice a lot being a single guy without a partner is you are not welcome to join in most social things with friends as they're mostly all couples and I'm not a woman (single women are always welcomed into social settings) so I have no 'natural appeal'.

I am not bothered because I usually don't socialise and my free time is devoted to my daughter. Nobody in my age range is interested in a single dad with a 5 y/o daughter.

The wedding reception I saw yesterday got me thinking because that was all couples from what I could tell.