The first card is Strength. This card represents balance and justice, but also a need to make thoughtful decisions with careful attention to detail. It could mean that you need to consider all aspects of long-term marriage before taking such a big step. It can also indicate that there are challenges to be faced before proceeding and that there will be tests to be overcome in order to arrive at a satisfactory solution.
The second card is Three of Swords reversed. The card represents the unhappiness, sadness and heartache associated with the idea of a long-term marriage. It could indicate that there are fears to address before proceeding, such as uncertainty and anxiety related to the future. But this card could also indicate that there is hope in this time of trouble. There are opportunities to resolve issues and find a compromise that is acceptable to both partners.
In conclusion, from the two selected tarot cards we can deduce that the chances of a long-term marriage depend on many factors. If all obstacles are overcome and fears are faced, there is a chance of finding an agreement that is satisfactory for both partners. However, it's important to take the time to consider all aspects before taking such a big step.