Have you read the sticky? The OP gave excellent examples on how to find these indicators. I hate to rehash, but you look for repetition. Go back to your past SR's for when you had relationships and you'll see something stick out.
For me, it's SR Venus conjunct my natal Saturn (5th house ruler) and both fall into the natal 7th. There are more indications---I was trying to sort it out recently.
Really? Do you use profections? As an aside, I don't know if I should be mentioning this because I'm still unsure, but I've noticed that when the lord of the year, and the SR Asc ruler are the same (planet or sign? not sure yet,) that the year was life changing and very important for me.
Okey, thanx, but sometimes the relationship is not so clearly marked in SR only in 7th or 5th house.
For example the year when I started my last relationship I had SR Uranus and SR South Node on SR Desc., Uranus is a ruler of my 8th house. SR Venus was in 4th SR. Mars, Neptune and Chiron in 5th SR. I don´t thing that this placement of planets in SR was so much special for relationship but maybe enough for starting a new one.
In the year when I began a passionate love story which never ended into a relationship, I had SR Venus conjuncted natal South Node in natal 8th and SR North Node conjucted my natal Venus in 7th. But I have nothing special in 5th or 7th SR. So maybe for that reason this romance never lead to relationship but had the most important meaning for me personally. I thing that that man was my karmic partner from past lives because in this case there were both conjunctions with SR and natal Venus and nodes. I attach a picture of this solar return.