Why would heir being homosexual make you quit? Hell, whenever I use ruler designer I -always- start as homosexual. The disadvantages are incredibly minor.
Homosexuals have children too. I tend to marry them to each other because I believe it would normally be unfair to couple them with straight persons.
Also, while in real life as a Catholic I believe that homosexual activity is immoral, I believe there is nothing immoral about merely being attracted to one's own gender and I refuse to "like" my in-game children, vassals, courtiers and others just because they have the trait. It is basically a challenge in life for them.
Also, I almost always quit because I've welded together half a dozen kingdoms and there is absolutely no challenge left.
Well, I don't know how you play but how about playing without fabricating claims, serially or too conveniently assassinating people, especially in combination with matrilineal marriages of claimants in your court who can't refuse a matrilineal marriage? Once we remove the gamey elements (and reduce the aggressive/greedy/dishonourable actions to characters with appropriate negative traits, or remove them at all from the game), then it stops being so easy.
In my first game, I started as Poland, never attempted a single assassination or fabrication, still got myself to 300 size, although only one kingdom (could have usurped one other but didn't want to because the king was legitimate).
For example, I once quit when I had conquered all of Iberia and France and hijacked the Caliphate. At that point I launched a Crusade against Mauritania then Africa then Sicily. Got tedious.
Well, don't need to hijack the caliphate, especially if it involves matrilineal marriages in combination with assassinations.
Another time I played as Duke of Kiev, converted to Catholicism, conquered all of Rus, most of Khazaria, and when the Golden Horde showed up, I swore fealty, raised my heir Mongol Catholic, took over the Horde, and then pressed a tribal Invasion on Poland and seized every single title and replaced them with Mongol Catholics. At that point the only thing left to do was keep pressing invasions and moving on.
Well, that's power-gaming. You can try and roleplay instead. Pressing tribal Mongol invasions on everybody is not particularly defensible from the point of view of Catholic theology.
Basically play like a normal person (or normal person with specific traits on the character list), not like someone who has a set of charts and indicators and very efficiently maximises his power base. Mediaeval monarchs didn't act like that (at least not to that extent, while they did fabricate claims, assassinate people tc.).
Another time I quit after I unified the HRE and the Shia Caliphate.
Why? I'd have kept playing. At any rate, again, if you did something like religious/cultural conversions from a power-gaming hand-on-the-mouse meta-gaming point of view, you could try and play without doing that. In my current game, I actually have a Byzantine claimant with kids belonging to my dynasty but I don't press it because I don't want a massive war with tens of thousands of Christian troops dying on both sides (I'd win it no doubt on my own but also the Kaiser is my brother-in-law).
Each time I started as a Duke or a Count. You spend the first few decades getting into position, then a few more pulling off something ridiculous,
Sorry if I sound preachy or boring but the "pulling off something ridiculous" may be the key to your dissatisfaction. Try to play the way you want, the way you like, the way you find fun, not the way that leads to maximising your final score or your power.
then a few more proving you can hold it together, then it's 1250 and there's nothing left to do.
There are some mongols coming yet.
At any rate, I really strong suggest that maybe playing one game in which you don't do massive powergaming (you have amply proven that you're capable to conquer half the world if you really mean it) but just simply play? In-character or in a historically reasonable way? Explore the benefits of having a good relationship with your liege and how it feels to be a loyal vassal? Or defender of your religion/culture/the poor peasants?
