A very significant article in JAMA Paediatrics says this:
The researchers found that suicide attempts by high school students decreased by 7 percent in states after they passed laws to legalize same-sex marriage, before the Supreme Court legalized it nationwide in 2015. Among LGB high school students, the decrease was especially concentrated, with suicide attempts falling by 14 percent.
But in states that did not legalize same-sex marriage, there was no change.
In the USA at least, suicide rates in all students, especially LGB students fall where same-sex marriage is legalised.
Love your LGBTIQ neighbour.