Lesbian video game characters in general are more prominent than gay male characters... that's an unfortunate truth... and it doesn't look like The Sims is an exception either. We live in a world where society is more accepting of lesbians VS gay men. This is a fact. Most of society (including straight women) are generally more comfortable with the idea of two women kissing, holding hands, etc, than they are about two men doing the same.
I mean, even back when The Sims was first released, Maxis showed two female Sims kissing... while there weren't any actual Sims who were represented as lesbian in the game itself, this didn't stop it from happening. Also, in Sims 3, a lesbian couple was featured in 'Roaring Heights' as well.
Back in 2015 (I think), The Sims created a picture for 'Pride Month', which featured a rainbow line of Sims couples... one thing that stood out to me was the fact that only a lesbian couple was represented with a child... while all the gay male couples were represented as single (ALL of them). The Sims also seems to have a bias when it comes to which "version" of a same-sex couple is acceptable to have children or not. This continues to be a trend in the actual game itself... the ONE and ONLY male same-sex couple (Brant and Brent Hecking) have a dog, but not an actual child... meanwhile, every female same-sex couple in the game so far seems to have a child, which furthers the stigma that lesbians are considered "acceptable" to be parents, while gay men aren't.
Even the new characters represented in the logo for The Sims 4 (after they did the "revamp"), features a female same-sex couple, as opposed to a male same-sex couple. Some might suggest that one of them is "gender non-binary", but let's be real here... they're meant to be seen as both female.
So, yes, I would agree that EA/Maxis seems to have a homophobia bias against gay men, but seem to be perfectly accepting of lesbians. This is, again, an unfortunate trend in video games in general... though, you'd think a game like The Sims would be more progressive in this area... but it's not, sadly.
Also, the fact that we can create gay male Sims on our own isn't the point... so don't bring that up as an argument (because I know many people will probably think of that)... the point is, the developers, whether intentional or not, have shown a bias in favor of lesbians, while seemingly showing a negative bias against gay men.