Just that really.
I've always had a fairly mixed group of friends, but i get on with guys better than girls on the most part.. i've noticed that when female friends get new partners, they tend to join the group as a whole, but the guys don't, they just tend to end up ghosting us.
There are also a couple of guys that i was really close friends with (nothing funny, just friends), we'd go to each others houses, out to the pub, watch films together...etc.. and that also stops soon as they have girlfriends.
Now i get that partners want to spend time with each other, but when they only see their new girlfriend at weekends, and have all week free, including one whole day when they don't work, and we always used to meet for coffee when they were single... aibu to be ticked off that i'm suddenly 'persona non grata' for simply being single/female... its like they're suddenly banned from being in my presence unsupervised 
i really feel like pointing out i was here/friends looooong before the girlfriend showed up.. if we'd wanted date/i'd been a threat we'd have been together already.