Modern ST does relationships decently most of the time. About the only pre-2017 ST that did relationships decently was DS9, and that was still hit and miss sometimes.
I know O’Brien and Keiko are the famous couple, but that’s still (usually) the old ‘Hectoring Wife ‘ and ‘Long-Suffering Husband seeking solace with his Best Male Friend’ set of cliches. Complete with a dartboard in a pub.
I think Trek’s attitude towards relationships pre DSC is hit and miss, but it’s attitude to sex before 2017 is juvenile in the extreme. Especially once Berman was in full swing.