OP, the problem with your first post is that you are thinking of marriage seemingly in terms of its being “the ONLY way of finding lasting, meaningful relationships”. This is the wrong way to think even without the gay/ straight issue.
You get married because you find someone who you absolutely want to have in your life every day on a daily basis. It is possible, though perhaps challenging, for a gay person to find an opposite-sex partner who makes them feel this way and for whom the sexual aspect may not be a big deal. However, you are marrying the specific person, not just getting married for the sake of not being alone or for the sake of fitting into societal expectations.
I was married 23 years (to someone I’d already been with for 10 years when we got married). I had a good marriage, to the point where as a widow it’s hard for me to see myself bothering with any other relationship. However, I did not get married in order to not be alone. And believe me when I say that even in a good marriage, you will have times of feeling very much alone, lonely, etc. I got married because I wanted to be in a marriage with a particular person I met. Not just for the sake of getting married itself.
When you have a particular person who makes you feel like you want to have them around in your life daily, even with all the ups and downs and occasional feelings of loneliness, isolation, anger, frustration, etc., then we can talk about marriage. But kicking the idea around hypothetically when you do not have any actual person in mind is just theoretical chit chat. Feel free to be open to the idea, but your first post pretty much says to me that you have a long way to go before you will be ready to get married, and it’s not because you’re gay or have SSA, it’s a matter of understanding what a day-to-day marital relationship is all about. Which is something you can probably only learn by having a long-term relationship with someone, not by reading posts or talking to priests or reading books on it.