"この結婚には三人いましたのでちょっと混み合っていました"

Simplified Meaning:

When someone says there were three people in a marriage, they mean that there was an extra person involved, which caused problems. This extra person might be another romantic interest, a friend, or even a family member who interferes too much. Imagine you and your partner trying to enjoy a romantic dinner, but a third person keeps joining you and talking over everything. This makes it hard for you and your partner to connect and feel close. In real life, this can happen when someone is having an affair, or even when a couple allows a friend or parent to influence their relationship too much. It creates tension and makes the relationship feel cramped and uncomfortable. For a healthier relationship, it's important to keep this outside influence in check and focus on the couple's connection. This advice helps couples to nurture their bond without letting external people create issues.