The basis of any relationship is a combination of honesty, trust, and commitment. However, certain circumstances or changes may give way to doubts about fidelity in a relationship.  In such cases, it is crucial to take a cautionary approach that involves open and clear communication for addressing issues like infidelity. To recognize and resolve the problem in a timely manner, one can watch out for the following signs that may indicate a partner is cheating:

1. Sudden changes in the schedule
A partner may suddenly rearrange their schedule to allocate more time to spend with someone outside the relationship. Here, frequent late work nights, additional work responsibilities, or suddenly spending more time away from home are common changes one may observe in their partner. 

2. Increase in social engagements
A sudden increase in social commitments or activities outside the regular routine of a partner could be seen as an unusual change. Unexpected work events, spending more time with friends, and a newfound interest in social activities could be observed. Sometimes, such inexplicable changes could indicate that a partner is having an affair.

3. Unexplained absences and trips
An unusual number of trips or unexplained absences may be indicative of something one wants to hide, like an affair. They may start making excuses, such as having to take sudden out-of-town trips or solo outings, to hide the fact that they are spending time with someone else. They may not have any valid explanation when asked about these absences.

4. Changes in sleeping pattern
A partner’s sleep pattern may change due to stress, health issues, and additional workload. So, it might not necessarily be a sign of infidelity. However, this development may be concerning if they have changed their sleep schedule to accommodate late-night calls or messages with someone outside the relationship. This sign must be addressed if the partner does not have a clear and valid reason for not sleeping well.

5. Neglecting responsibilities
If a partner is involved in an affair, their focus may shift to the new person. They may not seem to care about their usual responsibilities, like participating in household chores, performing familial duties, or keeping up with commitments they used to uphold earlier.

6. Additional effort in appearance
When trying to impress someone new, one may start taking a sudden interest in their appearance. They may adopt a new style or start buying trendy clothes without citing any clear reason for this change. They may also start caring more about how they look and begin working out more frequently. Changes in their grooming routine can also be observed.

7. Highly defensive behavior
A partner who is hiding something may start exhibiting defensive behavior. This can be observed when they are asked about the sudden change in their routine or habits, as they may become agitated when their behavior is questioned. They may also avoid giving direct answers or clear explanations.

8. Emotional distance
A partner suddenly becoming emotionally distant is often a sign of issues in the relationship. Several factors, like stress related to work, health, or family, can contribute to this change. However, the distance may develop if the partner becomes emotionally closer to someone else. 

To understand the causes of the abovementioned changes, initiating a conversation with the partner and addressing personal and relationship-related issues is important.