the gay act is a serious sin
There is no “gay act”. Same-sex partners engage in a variety of sexual acts, not all of them engage in all of the acts.
That’s actually part of the problem with same-sex marriage. There is no defining act (the procreative act) around which the entire sacrament coalesces.
You can annul a marriage for non-consummation. But how do you annul a same-sex “marriage” for non-consummation, if nobody agrees on what consummates a same-sex marriage?
Let’s say that a same-sex partner tries to argue for an annulment because his partner never engaged in act “A” but engaged in act “B”. The other partner argues that the “marriage” was “consummated” because he engaged in act “B” even though his partner thinks it wasn’t, because he prefers act “A” to act “B” and since his partner never engaged in the former, the “marriage” was “invalid”. It’s logical nonsense, because nobody agrees on what act consummates a same-sex “marriage”. The only way out, ISTM, would be to codify in the marriage contract an agreed-upon definition of “consummation” (this “marriage” is hereby consummated when both parties engage in act “X” to completion)… the whole notion of same-sex “marriage” is flawed at its most fundamental level. It may be a co-habitation partnership and I have no arguments against legal rights for those based on the notion that the state has no place in the bedrooms of consenting adults (it’s a moral issue, not a legal one), but it sure ain’t a “marriage”.
In a real marriage (either natural i.e. non-Catholic, or sacramental), the marriage is either consummated, or it isn’t, on the sole basis of the marital act. If the husband, for instance, is unhappy because his wife doesn’t engage in oral sex, but otherwise the marriage was consummated through the natural marital act, too bad, so sad, you don’t qualify for a non-consummation annulment.